diff --git a/src/Command/Attachments/CleanAttachmentsCommand.php b/src/Command/Attachments/CleanAttachmentsCommand.php
index 9c95b590..5db8e500 100644
--- a/src/Command/Attachments/CleanAttachmentsCommand.php
+++ b/src/Command/Attachments/CleanAttachmentsCommand.php
@@ -146,9 +146,9 @@ class CleanAttachmentsCommand extends Command
     /**
      * This function removes all empty folders inside $path. Taken from https://stackoverflow.com/a/1833681.
      *
-     * @param string $path The path in which the empty folders should be deleted
+     * @param  string  $path The path in which the empty folders should be deleted
      */
-    protected function removeEmptySubFolders($path): bool
+    protected function removeEmptySubFolders(string $path): bool
     {
         $empty = true;
         foreach (glob($path.DIRECTORY_SEPARATOR.'*') as $file) {
diff --git a/src/Command/Logs/ShowEventLogCommand.php b/src/Command/Logs/ShowEventLogCommand.php
index 00efffaf..7da5a6b7 100644
--- a/src/Command/Logs/ShowEventLogCommand.php
+++ b/src/Command/Logs/ShowEventLogCommand.php
@@ -76,7 +76,7 @@ class ShowEventLogCommand extends Command
         parent::__construct();
     }
 
-    public function execute(InputInterface $input, OutputInterface $output)
+    public function execute(InputInterface $input, OutputInterface $output): int
     {
         $io = new SymfonyStyle($input, $output);
 
diff --git a/src/Command/User/UserListCommand.php b/src/Command/User/UserListCommand.php
index ed8ceb53..08289e9c 100644
--- a/src/Command/User/UserListCommand.php
+++ b/src/Command/User/UserListCommand.php
@@ -31,7 +31,7 @@ class UserListCommand extends Command
         ;
     }
 
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         $io = new SymfonyStyle($input, $output);
 
diff --git a/src/Controller/AdminPages/ManufacturerController.php b/src/Controller/AdminPages/ManufacturerController.php
index 4fbb0535..4cf9c48f 100644
--- a/src/Controller/AdminPages/ManufacturerController.php
+++ b/src/Controller/AdminPages/ManufacturerController.php
@@ -71,7 +71,7 @@ class ManufacturerController extends BaseAdminController
      *
      * @return \Symfony\Component\HttpFoundation\RedirectResponse
      */
-    public function delete(Request $request, Manufacturer $entity, StructuralElementRecursionHelper $recursionHelper)
+    public function delete(Request $request, Manufacturer $entity, StructuralElementRecursionHelper $recursionHelper): \Symfony\Component\HttpFoundation\RedirectResponse
     {
         return $this->_delete($request, $entity, $recursionHelper);
     }
diff --git a/src/Controller/UserSettingsController.php b/src/Controller/UserSettingsController.php
index 7920b6b5..3428163d 100644
--- a/src/Controller/UserSettingsController.php
+++ b/src/Controller/UserSettingsController.php
@@ -59,6 +59,7 @@ use Symfony\Component\Form\Extension\Core\Type\PasswordType;
 use Symfony\Component\Form\Extension\Core\Type\RepeatedType;
 use Symfony\Component\Form\Extension\Core\Type\SubmitType;
 use Symfony\Component\Form\Extension\Core\Type\TextType;
+use Symfony\Component\Form\FormFactoryInterface;
 use Symfony\Component\HttpFoundation\RedirectResponse;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\PasswordHasher\Hasher\UserPasswordHasherInterface;
@@ -200,7 +201,7 @@ class UserSettingsController extends AbstractController
      *
      * @return RedirectResponse|\Symfony\Component\HttpFoundation\Response
      */
-    public function userSettings(Request $request, EntityManagerInterface $em, UserPasswordHasherInterface $passwordEncoder, GoogleAuthenticator $googleAuthenticator, BackupCodeManager $backupCodeManager)
+    public function userSettings(Request $request, EntityManagerInterface $em, UserPasswordHasherInterface $passwordEncoder, GoogleAuthenticator $googleAuthenticator, BackupCodeManager $backupCodeManager, FormFactoryInterface $formFactory)
     {
         /** @var User */
         $user = $this->getUser();
@@ -330,7 +331,8 @@ class UserSettingsController extends AbstractController
             return $this->redirectToRoute('user_settings');
         }
 
-        $backup_form = $this->get('form.factory')->createNamedBuilder('backup_codes')->add('reset_codes', SubmitType::class, [
+
+        $backup_form = $formFactory->createNamedBuilder('backup_codes')->add('reset_codes', SubmitType::class, [
             'label' => 'tfa_backup.regenerate_codes',
             'attr' => [
                 'class' => 'btn-danger',
diff --git a/src/DataTables/Column/EntityColumn.php b/src/DataTables/Column/EntityColumn.php
index 37ba7ea1..ea32440f 100644
--- a/src/DataTables/Column/EntityColumn.php
+++ b/src/DataTables/Column/EntityColumn.php
@@ -66,6 +66,7 @@ class EntityColumn extends AbstractColumn
      * The normalize function is responsible for converting parsed and processed data to a datatables-appropriate type.
      *
      * @param mixed $value The single value of the column
+     * @return mixed
      */
     public function normalize($value)
     {
@@ -73,7 +74,7 @@ class EntityColumn extends AbstractColumn
         return $value;
     }
 
-    public function configureOptions(OptionsResolver $resolver)
+    public function configureOptions(OptionsResolver $resolver): self
     {
         parent::configureOptions($resolver);
 
diff --git a/src/DataTables/Column/IconLinkColumn.php b/src/DataTables/Column/IconLinkColumn.php
index f97196f4..932b36a7 100644
--- a/src/DataTables/Column/IconLinkColumn.php
+++ b/src/DataTables/Column/IconLinkColumn.php
@@ -28,12 +28,16 @@ use Symfony\Component\OptionsResolver\OptionsResolver;
 
 class IconLinkColumn extends AbstractColumn
 {
+    /**
+     * @param $value
+     * @return mixed
+     */
     public function normalize($value)
     {
         return $value;
     }
 
-    public function configureOptions(OptionsResolver $resolver)
+    public function configureOptions(OptionsResolver $resolver): self
     {
         parent::configureOptions($resolver);
         $resolver->setDefaults([
@@ -51,7 +55,7 @@ class IconLinkColumn extends AbstractColumn
         return $this;
     }
 
-    public function render($value, $context)
+    public function render($value, $context): string
     {
         $href = $this->getHref($value, $context);
         $icon = $this->getIcon($value, $context);
diff --git a/src/DataTables/Column/LocaleDateTimeColumn.php b/src/DataTables/Column/LocaleDateTimeColumn.php
index c22311ed..87e7fd96 100644
--- a/src/DataTables/Column/LocaleDateTimeColumn.php
+++ b/src/DataTables/Column/LocaleDateTimeColumn.php
@@ -55,7 +55,12 @@ use Symfony\Component\OptionsResolver\OptionsResolver;
  */
 class LocaleDateTimeColumn extends AbstractColumn
 {
-    public function normalize($value)
+    /**
+     * @param $value
+     * @return bool|mixed|string
+     * @throws \Exception
+     */
+    public function normalize($value): string
     {
         if (null === $value) {
             return $this->options['nullValue'];
@@ -81,7 +86,7 @@ class LocaleDateTimeColumn extends AbstractColumn
         return $formatter->format($value->getTimestamp());
     }
 
-    protected function configureOptions(OptionsResolver $resolver)
+    protected function configureOptions(OptionsResolver $resolver): self
     {
         parent::configureOptions($resolver);
 
diff --git a/src/DataTables/Column/LogEntryExtraColumn.php b/src/DataTables/Column/LogEntryExtraColumn.php
index ee14d2b2..6e215479 100644
--- a/src/DataTables/Column/LogEntryExtraColumn.php
+++ b/src/DataTables/Column/LogEntryExtraColumn.php
@@ -57,12 +57,16 @@ class LogEntryExtraColumn extends AbstractColumn
         $this->formatter = $formatter;
     }
 
+    /**
+     * @param $value
+     * @return mixed
+     */
     public function normalize($value)
     {
         return $value;
     }
 
-    public function render($value, $context)
+    public function render($value, $context): string
     {
         return $this->formatter->format($context);
     }
diff --git a/src/DataTables/Column/LogEntryTargetColumn.php b/src/DataTables/Column/LogEntryTargetColumn.php
index 1314900f..b4d4a849 100644
--- a/src/DataTables/Column/LogEntryTargetColumn.php
+++ b/src/DataTables/Column/LogEntryTargetColumn.php
@@ -78,12 +78,16 @@ class LogEntryTargetColumn extends AbstractColumn
         $this->translator = $translator;
     }
 
+    /**
+     * @param $value
+     * @return mixed
+     */
     public function normalize($value)
     {
         return $value;
     }
 
-    public function configureOptions(OptionsResolver $resolver)
+    public function configureOptions(OptionsResolver $resolver): self
     {
         parent::configureOptions($resolver);
         $resolver->setDefault('show_associated', true);
@@ -92,7 +96,7 @@ class LogEntryTargetColumn extends AbstractColumn
         return $this;
     }
 
-    public function render($value, $context)
+    public function render($value, $context): string
     {
         if ($context instanceof UserNotAllowedLogEntry && $this->options['showAccessDeniedPath']) {
             return htmlspecialchars($context->getPath());
diff --git a/src/DataTables/Column/MarkdownColumn.php b/src/DataTables/Column/MarkdownColumn.php
index 20294f64..e20e22c2 100644
--- a/src/DataTables/Column/MarkdownColumn.php
+++ b/src/DataTables/Column/MarkdownColumn.php
@@ -58,6 +58,7 @@ class MarkdownColumn extends AbstractColumn
      * The normalize function is responsible for converting parsed and processed data to a datatables-appropriate type.
      *
      * @param mixed $value The single value of the column
+     * @return mixed
      */
     public function normalize($value)
     {
diff --git a/src/DataTables/Column/PartAttachmentsColumn.php b/src/DataTables/Column/PartAttachmentsColumn.php
index 885ac6dc..4692c74b 100644
--- a/src/DataTables/Column/PartAttachmentsColumn.php
+++ b/src/DataTables/Column/PartAttachmentsColumn.php
@@ -68,13 +68,14 @@ class PartAttachmentsColumn extends AbstractColumn
      * The normalize function is responsible for converting parsed and processed data to a datatables-appropriate type.
      *
      * @param mixed $value The single value of the column
+     * @return mixed
      */
     public function normalize($value)
     {
         return $value;
     }
 
-    public function render($value, $context)
+    public function render($value, $context): string
     {
         if (!$context instanceof Part) {
             throw new RuntimeException('$context must be a Part object!');
@@ -107,7 +108,7 @@ class PartAttachmentsColumn extends AbstractColumn
         return $tmp;
     }
 
-    public function configureOptions(OptionsResolver $resolver)
+    public function configureOptions(OptionsResolver $resolver): self
     {
         parent::configureOptions($resolver);
 
diff --git a/src/DataTables/Column/RevertLogColumn.php b/src/DataTables/Column/RevertLogColumn.php
index bd730d89..09db18fb 100644
--- a/src/DataTables/Column/RevertLogColumn.php
+++ b/src/DataTables/Column/RevertLogColumn.php
@@ -42,12 +42,16 @@ class RevertLogColumn extends AbstractColumn
         $this->security = $security;
     }
 
+    /**
+     * @param $value
+     * @return mixed
+     */
     public function normalize($value)
     {
         return $value;
     }
 
-    public function render($value, $context)
+    public function render($value, $context): string
     {
         if (
             $context instanceof CollectionElementDeleted
diff --git a/src/DataTables/Column/TagsColumn.php b/src/DataTables/Column/TagsColumn.php
index 678a151c..b0364cd7 100644
--- a/src/DataTables/Column/TagsColumn.php
+++ b/src/DataTables/Column/TagsColumn.php
@@ -58,6 +58,7 @@ class TagsColumn extends AbstractColumn
      * The normalize function is responsible for converting parsed and processed data to a datatables-appropriate type.
      *
      * @param mixed $value The single value of the column
+     * @return mixed
      */
     public function normalize($value)
     {
@@ -68,7 +69,7 @@ class TagsColumn extends AbstractColumn
         return explode(',', $value);
     }
 
-    public function render($tags, $context)
+    public function render($tags, $context): string
     {
         $html = '';
         $count = 10;
diff --git a/src/Doctrine/Purger/ResetAutoIncrementORMPurger.php b/src/Doctrine/Purger/ResetAutoIncrementORMPurger.php
index 527958af..f5d79b61 100644
--- a/src/Doctrine/Purger/ResetAutoIncrementORMPurger.php
+++ b/src/Doctrine/Purger/ResetAutoIncrementORMPurger.php
@@ -64,11 +64,11 @@ class ResetAutoIncrementORMPurger implements PurgerInterface, ORMPurgerInterface
     /**
      * Set the purge mode
      *
-     * @param int $mode
+     * @param  int  $mode
      *
      * @return void
      */
-    public function setPurgeMode($mode)
+    public function setPurgeMode(int $mode): void
     {
         $this->purgeMode = $mode;
     }
@@ -78,13 +78,13 @@ class ResetAutoIncrementORMPurger implements PurgerInterface, ORMPurgerInterface
      *
      * @return int
      */
-    public function getPurgeMode()
+    public function getPurgeMode(): int
     {
         return $this->purgeMode;
     }
 
     /** @inheritDoc */
-    public function setEntityManager(EntityManagerInterface $em)
+    public function setEntityManager(EntityManagerInterface $em): void
     {
         $this->em = $em;
     }
@@ -94,13 +94,13 @@ class ResetAutoIncrementORMPurger implements PurgerInterface, ORMPurgerInterface
      *
      * @return EntityManagerInterface
      */
-    public function getObjectManager()
+    public function getObjectManager(): ?EntityManagerInterface
     {
         return $this->em;
     }
 
     /** @inheritDoc */
-    public function purge()
+    public function purge(): void
     {
         $classes = [];
 
@@ -199,7 +199,7 @@ class ResetAutoIncrementORMPurger implements PurgerInterface, ORMPurgerInterface
      *
      * @return ClassMetadata[]
      */
-    private function getCommitOrder(EntityManagerInterface $em, array $classes)
+    private function getCommitOrder(EntityManagerInterface $em, array $classes): array
     {
         $sorter = new TopologicalSorter();
 
@@ -258,7 +258,7 @@ class ResetAutoIncrementORMPurger implements PurgerInterface, ORMPurgerInterface
      *
      * @return array
      */
-    private function getAssociationTables(array $classes, AbstractPlatform $platform)
+    private function getAssociationTables(array $classes, AbstractPlatform $platform): array
     {
         $associationTables = [];
 
diff --git a/src/Entity/Base/AbstractCompany.php b/src/Entity/Base/AbstractCompany.php
index e9912b9b..3ff32987 100644
--- a/src/Entity/Base/AbstractCompany.php
+++ b/src/Entity/Base/AbstractCompany.php
@@ -150,12 +150,12 @@ abstract class AbstractCompany extends AbstractPartsContainingDBElement
     /**
      * Get the link to the website of an article.
      *
-     * @param string $partnr * NULL for returning the URL with a placeholder for the part number
+     * @param  string|null  $partnr * NULL for returning the URL with a placeholder for the part number
      *                       * or the part number for returning the direct URL to the article
      *
      * @return string the link to the article
      */
-    public function getAutoProductUrl($partnr = null): string
+    public function getAutoProductUrl(string $partnr = null): string
     {
         if (is_string($partnr)) {
             return str_replace('%PARTNUMBER%', $partnr, $this->auto_product_url);
diff --git a/src/Entity/UserSystem/U2FKey.php b/src/Entity/UserSystem/U2FKey.php
index 000c062b..b7f8f6da 100644
--- a/src/Entity/UserSystem/U2FKey.php
+++ b/src/Entity/UserSystem/U2FKey.php
@@ -120,11 +120,12 @@ class U2FKey implements TwoFactorKeyInterface
         $this->counter = $data->counter;
     }
 
-    public function getKeyHandle()
+    public function getKeyHandle(): string
     {
         return $this->keyHandle;
     }
 
+
     public function setKeyHandle($keyHandle): self
     {
         $this->keyHandle = $keyHandle;
@@ -132,7 +133,7 @@ class U2FKey implements TwoFactorKeyInterface
         return $this;
     }
 
-    public function getPublicKey()
+    public function getPublicKey(): string
     {
         return $this->publicKey;
     }
@@ -144,7 +145,7 @@ class U2FKey implements TwoFactorKeyInterface
         return $this;
     }
 
-    public function getCertificate()
+    public function getCertificate(): string
     {
         return $this->certificate;
     }
@@ -156,7 +157,7 @@ class U2FKey implements TwoFactorKeyInterface
         return $this;
     }
 
-    public function getCounter()
+    public function getCounter(): int
     {
         return $this->counter;
     }
@@ -168,7 +169,7 @@ class U2FKey implements TwoFactorKeyInterface
         return $this;
     }
 
-    public function getName()
+    public function getName(): string
     {
         return $this->name;
     }
diff --git a/src/EventSubscriber/LogSystem/EventLoggerSubscriber.php b/src/EventSubscriber/LogSystem/EventLoggerSubscriber.php
index 1fb8ea7d..e12ba158 100644
--- a/src/EventSubscriber/LogSystem/EventLoggerSubscriber.php
+++ b/src/EventSubscriber/LogSystem/EventLoggerSubscriber.php
@@ -213,7 +213,7 @@ class EventLoggerSubscriber implements EventSubscriber
         return true;
     }
 
-    public function getSubscribedEvents()
+    public function getSubscribedEvents(): array
     {
         return[
             Events::onFlush,
diff --git a/src/EventSubscriber/LogSystem/LogAccessDeniedSubscriber.php b/src/EventSubscriber/LogSystem/LogAccessDeniedSubscriber.php
index 70eade97..ae3e5e0f 100644
--- a/src/EventSubscriber/LogSystem/LogAccessDeniedSubscriber.php
+++ b/src/EventSubscriber/LogSystem/LogAccessDeniedSubscriber.php
@@ -58,7 +58,7 @@ class LogAccessDeniedSubscriber implements EventSubscriberInterface
         $this->logger->logAndFlush($log_entry);
     }
 
-    public static function getSubscribedEvents()
+    public static function getSubscribedEvents(): array
     {
         return ['kernel.exception' => 'onKernelException'];
     }
diff --git a/src/EventSubscriber/LogSystem/LogDBMigrationSubscriber.php b/src/EventSubscriber/LogSystem/LogDBMigrationSubscriber.php
index ac63f63a..ee6f5c3c 100644
--- a/src/EventSubscriber/LogSystem/LogDBMigrationSubscriber.php
+++ b/src/EventSubscriber/LogSystem/LogDBMigrationSubscriber.php
@@ -102,7 +102,7 @@ class LogDBMigrationSubscriber implements EventSubscriber
         }
     }
 
-    public function getSubscribedEvents()
+    public function getSubscribedEvents(): array
     {
         return [
             Events::onMigrationsMigrated,
diff --git a/src/Form/AttachmentFormType.php b/src/Form/AttachmentFormType.php
index ef8a1c6d..22368f46 100644
--- a/src/Form/AttachmentFormType.php
+++ b/src/Form/AttachmentFormType.php
@@ -185,7 +185,7 @@ class AttachmentFormType extends AbstractType
         ]);
     }
 
-    public function getBlockPrefix()
+    public function getBlockPrefix(): string
     {
         return 'attachment';
     }
diff --git a/src/Form/Permissions/PermissionsMapper.php b/src/Form/Permissions/PermissionsMapper.php
index 321754bb..657c68ea 100644
--- a/src/Form/Permissions/PermissionsMapper.php
+++ b/src/Form/Permissions/PermissionsMapper.php
@@ -72,7 +72,7 @@ final class PermissionsMapper implements DataMapperInterface
      * @param mixed                       $viewData View data of the compound form being initialized
      * @param FormInterface[]|Traversable $forms    A list of {@link FormInterface} instances
      */
-    public function mapDataToForms($viewData, $forms)
+    public function mapDataToForms($viewData, $forms): void
     {
         foreach ($forms as $form) {
             if ($this->inherit) {
diff --git a/src/Form/Type/BigDecimalMoneyType.php b/src/Form/Type/BigDecimalMoneyType.php
index 0d77abaa..9ad368af 100644
--- a/src/Form/Type/BigDecimalMoneyType.php
+++ b/src/Form/Type/BigDecimalMoneyType.php
@@ -33,12 +33,12 @@ class BigDecimalMoneyType extends AbstractType implements DataTransformerInterfa
         $builder->addModelTransformer($this);
     }
 
-    public function getParent()
+    public function getParent(): string
     {
         return MoneyType::class;
     }
 
-    public function transform($value)
+    public function transform($value): ?string
     {
         if (null === $value) {
             return null;
@@ -51,7 +51,7 @@ class BigDecimalMoneyType extends AbstractType implements DataTransformerInterfa
         return $value;
     }
 
-    public function reverseTransform($value)
+    public function reverseTransform($value): ?BigDecimal
     {
         if (null === $value) {
             return null;
diff --git a/src/Form/Type/BigDecimalNumberType.php b/src/Form/Type/BigDecimalNumberType.php
index 00863914..3ea9db78 100644
--- a/src/Form/Type/BigDecimalNumberType.php
+++ b/src/Form/Type/BigDecimalNumberType.php
@@ -33,12 +33,12 @@ class BigDecimalNumberType extends AbstractType implements DataTransformerInterf
         $builder->addModelTransformer($this);
     }
 
-    public function getParent()
+    public function getParent(): string
     {
         return NumberType::class;
     }
 
-    public function transform($value)
+    public function transform($value): ?string
     {
         if (null === $value) {
             return null;
@@ -51,7 +51,7 @@ class BigDecimalNumberType extends AbstractType implements DataTransformerInterf
         return $value;
     }
 
-    public function reverseTransform($value)
+    public function reverseTransform($value): ?BigDecimal
     {
         if (null === $value) {
             return null;
diff --git a/src/Form/Type/MasterPictureAttachmentType.php b/src/Form/Type/MasterPictureAttachmentType.php
index d4b3af9f..725dd90b 100644
--- a/src/Form/Type/MasterPictureAttachmentType.php
+++ b/src/Form/Type/MasterPictureAttachmentType.php
@@ -96,7 +96,7 @@ class MasterPictureAttachmentType extends AbstractType
         $resolver->setAllowedValues('filter', ['', 'picture', '3d_model']);
     }
 
-    public function getParent()
+    public function getParent(): string
     {
         return ChoiceType::class;
     }
diff --git a/src/Form/Type/RichTextEditorType.php b/src/Form/Type/RichTextEditorType.php
index 3424b8a0..651b3eb9 100644
--- a/src/Form/Type/RichTextEditorType.php
+++ b/src/Form/Type/RichTextEditorType.php
@@ -21,7 +21,7 @@ class RichTextEditorType extends AbstractType
 
     }
 
-    public function getBlockPrefix()
+    public function getBlockPrefix(): string
     {
         return 'rich_text_editor';
     }
@@ -33,7 +33,7 @@ class RichTextEditorType extends AbstractType
         parent::finishView($view, $form, $options); // TODO: Change the autogenerated stub
     }
 
-    protected function optionsToAttrArray(array $options)
+    protected function optionsToAttrArray(array $options): array
     {
         $tmp = [];
 
@@ -49,7 +49,7 @@ class RichTextEditorType extends AbstractType
         return $tmp;
     }
 
-    public function getParent()
+    public function getParent(): string
     {
         return TextareaType::class;
     }
diff --git a/src/Form/Type/SIUnitType.php b/src/Form/Type/SIUnitType.php
index d0ae852c..ba1dc7f4 100644
--- a/src/Form/Type/SIUnitType.php
+++ b/src/Form/Type/SIUnitType.php
@@ -176,7 +176,7 @@ final class SIUnitType extends AbstractType implements DataMapperInterface
      *
      * @throws Exception\UnexpectedTypeException if the type of the data parameter is not supported
      */
-    public function mapDataToForms($viewData, $forms)
+    public function mapDataToForms($viewData, $forms): void
     {
         $forms = iterator_to_array($forms);
 
diff --git a/src/Form/Type/StructuralEntityType.php b/src/Form/Type/StructuralEntityType.php
index 60911e4d..dd233d18 100644
--- a/src/Form/Type/StructuralEntityType.php
+++ b/src/Form/Type/StructuralEntityType.php
@@ -148,7 +148,7 @@ class StructuralEntityType extends AbstractType
         parent::buildView($view, $form, $options);
     }
 
-    public function getParent()
+    public function getParent(): string
     {
         return ChoiceType::class;
     }
diff --git a/src/Form/Type/TriStateCheckboxType.php b/src/Form/Type/TriStateCheckboxType.php
index 17c15a58..87bdc473 100644
--- a/src/Form/Type/TriStateCheckboxType.php
+++ b/src/Form/Type/TriStateCheckboxType.php
@@ -68,7 +68,7 @@ final class TriStateCheckboxType extends AbstractType implements DataTransformer
         ]);
     }
 
-    public function getBlockPrefix()
+    public function getBlockPrefix(): string
     {
         return 'tristate';
     }
diff --git a/src/Helpers/BigDecimalType.php b/src/Helpers/BigDecimalType.php
index 4934e543..d953dfb0 100644
--- a/src/Helpers/BigDecimalType.php
+++ b/src/Helpers/BigDecimalType.php
@@ -28,7 +28,7 @@ class BigDecimalType extends Type
 {
     public const BIG_DECIMAL = 'big_decimal';
 
-    public function getSQLDeclaration(array $fieldDeclaration, AbstractPlatform $platform)
+    public function getSQLDeclaration(array $fieldDeclaration, AbstractPlatform $platform): string
     {
         return $platform->getDecimalTypeDeclarationSQL($fieldDeclaration);
     }
@@ -50,7 +50,7 @@ class BigDecimalType extends Type
     /**
      * @param BigDecimal|null $value
      */
-    public function convertToDatabaseValue($value, AbstractPlatform $platform)
+    public function convertToDatabaseValue($value, AbstractPlatform $platform): ?string
     {
         if (null === $value) {
             return null;
@@ -59,12 +59,12 @@ class BigDecimalType extends Type
         return (string) $value;
     }
 
-    public function getName()
+    public function getName(): string
     {
         return self::BIG_DECIMAL;
     }
 
-    public function requiresSQLCommentHint(AbstractPlatform $platform)
+    public function requiresSQLCommentHint(AbstractPlatform $platform): bool
     {
         return true;
     }
diff --git a/src/Helpers/LabelResponse.php b/src/Helpers/LabelResponse.php
index 8561852c..c9b763b8 100644
--- a/src/Helpers/LabelResponse.php
+++ b/src/Helpers/LabelResponse.php
@@ -33,7 +33,7 @@ class LabelResponse extends Response
         parent::__construct($content, $status, $headers);
     }
 
-    public function setContent($content)
+    public function setContent($content): self
     {
         parent::setContent($content);
 
@@ -43,7 +43,7 @@ class LabelResponse extends Response
         return $this;
     }
 
-    public function prepare(Request $request)
+    public function prepare(Request $request): self
     {
         parent::prepare($request);
 
@@ -81,13 +81,13 @@ class LabelResponse extends Response
     /**
      * Sets the Content-Disposition header with the given filename.
      *
-     * @param string $disposition      ResponseHeaderBag::DISPOSITION_INLINE or ResponseHeaderBag::DISPOSITION_ATTACHMENT
-     * @param string $filename         Optionally use this UTF-8 encoded filename instead of the real name of the file
-     * @param string $filenameFallback A fallback filename, containing only ASCII characters. Defaults to an automatically encoded filename
+     * @param  string  $disposition      ResponseHeaderBag::DISPOSITION_INLINE or ResponseHeaderBag::DISPOSITION_ATTACHMENT
+     * @param  string  $filename         Optionally use this UTF-8 encoded filename instead of the real name of the file
+     * @param  string  $filenameFallback A fallback filename, containing only ASCII characters. Defaults to an automatically encoded filename
      *
      * @return $this
      */
-    public function setContentDisposition($disposition, $filename, $filenameFallback = ''): self
+    public function setContentDisposition(string $disposition, string $filename, string $filenameFallback = ''): self
     {
         if ('' === $filenameFallback && (!preg_match('/^[\x20-\x7e]*$/', $filename) || false !== strpos($filename, '%'))) {
             $encoding = mb_detect_encoding($filename, null, true) ?: '8bit';
diff --git a/src/Helpers/Trees/TreeViewNodeState.php b/src/Helpers/Trees/TreeViewNodeState.php
index 3fa33758..9019e950 100644
--- a/src/Helpers/Trees/TreeViewNodeState.php
+++ b/src/Helpers/Trees/TreeViewNodeState.php
@@ -94,7 +94,7 @@ final class TreeViewNodeState implements JsonSerializable
         return $this;
     }
 
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $ret = [];
         if (null !== $this->selected) {
diff --git a/src/Helpers/UTCDateTimeType.php b/src/Helpers/UTCDateTimeType.php
index d6a02f2a..73e83f2b 100644
--- a/src/Helpers/UTCDateTimeType.php
+++ b/src/Helpers/UTCDateTimeType.php
@@ -56,7 +56,7 @@ class UTCDateTimeType extends DateTimeType
 {
     private static $utc_timezone;
 
-    public function convertToDatabaseValue($value, AbstractPlatform $platform)
+    public function convertToDatabaseValue($value, AbstractPlatform $platform): ?string
     {
         if (!self::$utc_timezone) {
             self::$utc_timezone = new DateTimeZone('UTC');
@@ -69,7 +69,7 @@ class UTCDateTimeType extends DateTimeType
         return parent::convertToDatabaseValue($value, $platform);
     }
 
-    public function convertToPHPValue($value, AbstractPlatform $platform)
+    public function convertToPHPValue($value, AbstractPlatform $platform): ?DateTime
     {
         if (!self::$utc_timezone) {
             self::$utc_timezone = new DateTimeZone('UTC');
diff --git a/src/Repository/LogEntryRepository.php b/src/Repository/LogEntryRepository.php
index 8e8c2e27..8f973425 100644
--- a/src/Repository/LogEntryRepository.php
+++ b/src/Repository/LogEntryRepository.php
@@ -52,7 +52,7 @@ use App\Entity\UserSystem\User;
 
 class LogEntryRepository extends DBElementRepository
 {
-    public function findBy(array $criteria, ?array $orderBy = null, $limit = null, $offset = null)
+    public function findBy(array $criteria, ?array $orderBy = null, $limit = null, $offset = null): array
     {
         //Emulate a target element criteria by splitting it manually in the needed criterias
         if (isset($criteria['target']) && $criteria['target'] instanceof AbstractDBElement) {
@@ -70,13 +70,13 @@ class LogEntryRepository extends DBElementRepository
      * Find log entries associated with the given element (the history of the element).
      *
      * @param AbstractDBElement $element The element for which the history should be generated
-     * @param string            $order   By default newest entries are shown first. Change this to ASC to show oldest entries first.
+     * @param  string  $order   By default newest entries are shown first. Change this to ASC to show oldest entries first.
      * @param null              $limit
      * @param null              $offset
      *
      * @return AbstractLogEntry[]
      */
-    public function getElementHistory(AbstractDBElement $element, $order = 'DESC', $limit = null, $offset = null): array
+    public function getElementHistory(AbstractDBElement $element, string $order = 'DESC', $limit = null, $offset = null): array
     {
         return $this->findBy(['element' => $element], ['timestamp' => $order], $limit, $offset);
     }
@@ -175,11 +175,11 @@ class LogEntryRepository extends DBElementRepository
     /**
      * Gets the last log entries ordered by timestamp.
      *
-     * @param string $order
+     * @param  string  $order
      * @param null   $limit
      * @param null   $offset
      */
-    public function getLogsOrderedByTimestamp($order = 'DESC', $limit = null, $offset = null): array
+    public function getLogsOrderedByTimestamp(string $order = 'DESC', $limit = null, $offset = null): array
     {
         return $this->findBy([], ['timestamp' => $order], $limit, $offset);
     }
@@ -226,7 +226,7 @@ class LogEntryRepository extends DBElementRepository
         return $this->getLastUser($element, ElementCreatedLogEntry::class);
     }
 
-    protected function getLastUser(AbstractDBElement $element, string $class)
+    protected function getLastUser(AbstractDBElement $element, string $class): ?User
     {
         $qb = $this->createQueryBuilder('log');
         $qb->select('log')
diff --git a/src/Security/Voter/AttachmentVoter.php b/src/Security/Voter/AttachmentVoter.php
index 6493147f..b5b7b7ba 100644
--- a/src/Security/Voter/AttachmentVoter.php
+++ b/src/Security/Voter/AttachmentVoter.php
@@ -52,9 +52,9 @@ class AttachmentVoter extends ExtendedVoter
      * Similar to voteOnAttribute, but checking for the anonymous user is already done.
      * The current user (or the anonymous user) is passed by $user.
      *
-     * @param string $attribute
+     * @param  string  $attribute
      */
-    protected function voteOnUser($attribute, $subject, User $user): bool
+    protected function voteOnUser(string $attribute, $subject, User $user): bool
     {
         return $this->resolver->inherit($user, 'parts_attachments', $attribute) ?? false;
     }
@@ -62,12 +62,12 @@ class AttachmentVoter extends ExtendedVoter
     /**
      * Determines if the attribute and subject are supported by this voter.
      *
-     * @param string $attribute An attribute
+     * @param  string  $attribute An attribute
      * @param mixed  $subject   The subject to secure, e.g. an object the user wants to access or any other PHP type
      *
      * @return bool True if the attribute and subject are supported, false otherwise
      */
-    protected function supports($attribute, $subject)
+    protected function supports(string $attribute, $subject): bool
     {
         if (is_a($subject, Attachment::class, true)) {
             return in_array($attribute, $this->resolver->listOperationsForPermission('parts_attachments'), false);
diff --git a/src/Security/Voter/ExtendedVoter.php b/src/Security/Voter/ExtendedVoter.php
index d7545b42..279e9d63 100644
--- a/src/Security/Voter/ExtendedVoter.php
+++ b/src/Security/Voter/ExtendedVoter.php
@@ -92,7 +92,7 @@ abstract class ExtendedVoter extends Voter
      * Similar to voteOnAttribute, but checking for the anonymous user is already done.
      * The current user (or the anonymous user) is passed by $user.
      *
-     * @param string $attribute
+     * @param  string  $attribute
      */
-    abstract protected function voteOnUser($attribute, $subject, User $user): bool;
+    abstract protected function voteOnUser(string $attribute, $subject, User $user): bool;
 }
diff --git a/src/Security/Voter/GroupVoter.php b/src/Security/Voter/GroupVoter.php
index 5c507145..a1fa190f 100644
--- a/src/Security/Voter/GroupVoter.php
+++ b/src/Security/Voter/GroupVoter.php
@@ -51,9 +51,9 @@ class GroupVoter extends ExtendedVoter
      * Similar to voteOnAttribute, but checking for the anonymous user is already done.
      * The current user (or the anonymous user) is passed by $user.
      *
-     * @param string $attribute
+     * @param  string  $attribute
      */
-    protected function voteOnUser($attribute, $subject, User $user): bool
+    protected function voteOnUser(string $attribute, $subject, User $user): bool
     {
         return $this->resolver->inherit($user, 'groups', $attribute) ?? false;
     }
@@ -61,12 +61,12 @@ class GroupVoter extends ExtendedVoter
     /**
      * Determines if the attribute and subject are supported by this voter.
      *
-     * @param string $attribute An attribute
+     * @param  string  $attribute An attribute
      * @param mixed  $subject   The subject to secure, e.g. an object the user wants to access or any other PHP type
      *
      * @return bool True if the attribute and subject are supported, false otherwise
      */
-    protected function supports($attribute, $subject)
+    protected function supports(string $attribute, $subject): bool
     {
         if (is_a($subject, Group::class, true)) {
             return $this->resolver->isValidOperation('groups', $attribute);
diff --git a/src/Security/Voter/LabelProfileVoter.php b/src/Security/Voter/LabelProfileVoter.php
index 5526cdb1..37823ec6 100644
--- a/src/Security/Voter/LabelProfileVoter.php
+++ b/src/Security/Voter/LabelProfileVoter.php
@@ -37,12 +37,12 @@ class LabelProfileVoter extends ExtendedVoter
         'revert_element' => 'revert_element',
     ];
 
-    protected function voteOnUser($attribute, $subject, User $user): bool
+    protected function voteOnUser(string $attribute, $subject, User $user): bool
     {
         return $this->resolver->inherit($user, 'labels', self::MAPPING[$attribute]) ?? false;
     }
 
-    protected function supports($attribute, $subject)
+    protected function supports($attribute, $subject): bool
     {
         if ($subject instanceof LabelProfile) {
             if (!isset(self::MAPPING[$attribute])) {
diff --git a/src/Security/Voter/LogEntryVoter.php b/src/Security/Voter/LogEntryVoter.php
index 24fe857a..bc9b6db8 100644
--- a/src/Security/Voter/LogEntryVoter.php
+++ b/src/Security/Voter/LogEntryVoter.php
@@ -49,7 +49,7 @@ class LogEntryVoter extends ExtendedVoter
 {
     public const ALLOWED_OPS = ['read', 'delete'];
 
-    protected function voteOnUser($attribute, $subject, User $user): bool
+    protected function voteOnUser(string $attribute, $subject, User $user): bool
     {
         if ('delete' === $attribute) {
             return $this->resolver->inherit($user, 'system', 'delete_logs') ?? false;
@@ -70,7 +70,7 @@ class LogEntryVoter extends ExtendedVoter
         return false;
     }
 
-    protected function supports($attribute, $subject)
+    protected function supports($attribute, $subject): bool
     {
         if ($subject instanceof AbstractLogEntry) {
             return in_array($subject, static::ALLOWED_OPS, true);
diff --git a/src/Security/Voter/OrderdetailVoter.php b/src/Security/Voter/OrderdetailVoter.php
index 0d54d391..84a2b739 100644
--- a/src/Security/Voter/OrderdetailVoter.php
+++ b/src/Security/Voter/OrderdetailVoter.php
@@ -33,7 +33,7 @@ class OrderdetailVoter extends ExtendedVoter
      */
     protected const PART_PERMS = ['show_history', 'revert_element'];
 
-    protected function voteOnUser($attribute, $subject, User $user): bool
+    protected function voteOnUser(string $attribute, $subject, User $user): bool
     {
         if (in_array($attribute, self::PART_PERMS, true)) {
             return $this->resolver->inherit($user, 'parts', $attribute) ?? false;
@@ -42,7 +42,7 @@ class OrderdetailVoter extends ExtendedVoter
         return $this->resolver->inherit($user, 'parts_orderdetails', $attribute) ?? false;
     }
 
-    protected function supports($attribute, $subject)
+    protected function supports($attribute, $subject): bool
     {
         if (is_a($subject, Orderdetail::class, true)) {
             return in_array($attribute, array_merge(
diff --git a/src/Security/Voter/PartLotVoter.php b/src/Security/Voter/PartLotVoter.php
index 035d25b5..2fc8f608 100644
--- a/src/Security/Voter/PartLotVoter.php
+++ b/src/Security/Voter/PartLotVoter.php
@@ -33,7 +33,7 @@ class PartLotVoter extends ExtendedVoter
      */
     protected const PART_PERMS = ['show_history', 'revert_element'];
 
-    protected function voteOnUser($attribute, $subject, User $user): bool
+    protected function voteOnUser(string $attribute, $subject, User $user): bool
     {
         if (in_array($attribute, self::PART_PERMS, true)) {
             return $this->resolver->inherit($user, 'parts', $attribute) ?? false;
@@ -42,7 +42,7 @@ class PartLotVoter extends ExtendedVoter
         return $this->resolver->inherit($user, 'parts_lots', $attribute) ?? false;
     }
 
-    protected function supports($attribute, $subject)
+    protected function supports($attribute, $subject): bool
     {
         if (is_a($subject, PartLot::class, true)) {
             return in_array($attribute, array_merge(
diff --git a/src/Security/Voter/PartVoter.php b/src/Security/Voter/PartVoter.php
index 75de92fa..cfbc66be 100644
--- a/src/Security/Voter/PartVoter.php
+++ b/src/Security/Voter/PartVoter.php
@@ -54,7 +54,7 @@ class PartVoter extends ExtendedVoter
 {
     public const READ = 'read';
 
-    protected function supports($attribute, $subject)
+    protected function supports($attribute, $subject): bool
     {
         if (is_a($subject, Part::class, true)) {
             //Check if a sub permission should be checked -> $attribute has format name.edit
@@ -71,7 +71,7 @@ class PartVoter extends ExtendedVoter
         return false;
     }
 
-    protected function voteOnUser($attribute, $subject, User $user): bool
+    protected function voteOnUser(string $attribute, $subject, User $user): bool
     {
         //Check for sub permissions
         if (false !== strpos($attribute, '.')) {
diff --git a/src/Security/Voter/PermissionVoter.php b/src/Security/Voter/PermissionVoter.php
index 32383a80..7632d39d 100644
--- a/src/Security/Voter/PermissionVoter.php
+++ b/src/Security/Voter/PermissionVoter.php
@@ -55,9 +55,9 @@ class PermissionVoter extends ExtendedVoter
      * Similar to voteOnAttribute, but checking for the anonymous user is already done.
      * The current user (or the anonymous user) is passed by $user.
      *
-     * @param string $attribute
+     * @param  string  $attribute
      */
-    protected function voteOnUser($attribute, $subject, User $user): bool
+    protected function voteOnUser(string $attribute, $subject, User $user): bool
     {
         $attribute = ltrim($attribute, '@');
         [$perm, $op] = explode('.', $attribute);
@@ -68,12 +68,12 @@ class PermissionVoter extends ExtendedVoter
     /**
      * Determines if the attribute and subject are supported by this voter.
      *
-     * @param string $attribute An attribute
+     * @param  string  $attribute An attribute
      * @param mixed  $subject   The subject to secure, e.g. an object the user wants to access or any other PHP type
      *
      * @return bool True if the attribute and subject are supported, false otherwise
      */
-    protected function supports($attribute, $subject)
+    protected function supports(string $attribute, $subject): bool
     {
         //Check if the attribute has the form @permission.operation
         if (preg_match('#^@\\w+\\.\\w+$#', $attribute)) {
diff --git a/src/Security/Voter/PricedetailVoter.php b/src/Security/Voter/PricedetailVoter.php
index c6a9cbdc..b21b367f 100644
--- a/src/Security/Voter/PricedetailVoter.php
+++ b/src/Security/Voter/PricedetailVoter.php
@@ -33,7 +33,7 @@ class PricedetailVoter extends ExtendedVoter
      */
     protected const PART_PERMS = ['show_history', 'revert_element'];
 
-    protected function voteOnUser($attribute, $subject, User $user): bool
+    protected function voteOnUser(string $attribute, $subject, User $user): bool
     {
         if (in_array($attribute, self::PART_PERMS, true)) {
             return $this->resolver->inherit($user, 'parts', $attribute) ?? false;
@@ -42,7 +42,7 @@ class PricedetailVoter extends ExtendedVoter
         return $this->resolver->inherit($user, 'parts_prices', $attribute) ?? false;
     }
 
-    protected function supports($attribute, $subject)
+    protected function supports($attribute, $subject): bool
     {
         if (is_a($subject, Pricedetail::class, true)) {
             return in_array($attribute, array_merge(
diff --git a/src/Security/Voter/StructureVoter.php b/src/Security/Voter/StructureVoter.php
index 0161667f..3b5bc330 100644
--- a/src/Security/Voter/StructureVoter.php
+++ b/src/Security/Voter/StructureVoter.php
@@ -72,12 +72,12 @@ class StructureVoter extends ExtendedVoter
     /**
      * Determines if the attribute and subject are supported by this voter.
      *
-     * @param string $attribute An attribute
+     * @param  string  $attribute An attribute
      * @param mixed  $subject   The subject to secure, e.g. an object the user wants to access or any other PHP type
      *
      * @return bool True if the attribute and subject are supported, false otherwise
      */
-    protected function supports($attribute, $subject)
+    protected function supports(string $attribute, $subject): bool
     {
         if (is_object($subject) || is_string($subject)) {
             $permission_name = $this->instanceToPermissionName($subject);
@@ -121,9 +121,9 @@ class StructureVoter extends ExtendedVoter
      * Similar to voteOnAttribute, but checking for the anonymous user is already done.
      * The current user (or the anonymous user) is passed by $user.
      *
-     * @param string $attribute
+     * @param  string  $attribute
      */
-    protected function voteOnUser($attribute, $subject, User $user): bool
+    protected function voteOnUser(string $attribute, $subject, User $user): bool
     {
         $permission_name = $this->instanceToPermissionName($subject);
         //Just resolve the permission
diff --git a/src/Security/Voter/UserVoter.php b/src/Security/Voter/UserVoter.php
index ecdd186d..af2d6700 100644
--- a/src/Security/Voter/UserVoter.php
+++ b/src/Security/Voter/UserVoter.php
@@ -50,12 +50,12 @@ class UserVoter extends ExtendedVoter
     /**
      * Determines if the attribute and subject are supported by this voter.
      *
-     * @param string $attribute An attribute
+     * @param  string  $attribute An attribute
      * @param mixed  $subject   The subject to secure, e.g. an object the user wants to access or any other PHP type
      *
      * @return bool True if the attribute and subject are supported, false otherwise
      */
-    protected function supports($attribute, $subject)
+    protected function supports(string $attribute, $subject): bool
     {
         if (is_a($subject, User::class, true)) {
             return in_array($attribute, array_merge(
@@ -72,9 +72,9 @@ class UserVoter extends ExtendedVoter
      * Similar to voteOnAttribute, but checking for the anonymous user is already done.
      * The current user (or the anonymous user) is passed by $user.
      *
-     * @param string $attribute
+     * @param  string  $attribute
      */
-    protected function voteOnUser($attribute, $subject, User $user): bool
+    protected function voteOnUser(string $attribute, $subject, User $user): bool
     {
         //Check if the checked user is the user itself
         if (($subject instanceof User) && $subject->getID() === $user->getID() &&
diff --git a/src/Services/Attachments/AttachmentManager.php b/src/Services/Attachments/AttachmentManager.php
index 66c8d7df..dccaa781 100644
--- a/src/Services/Attachments/AttachmentManager.php
+++ b/src/Services/Attachments/AttachmentManager.php
@@ -163,11 +163,11 @@ class AttachmentManager
      * Returns a human readable version of the attachment file size.
      * For external attachments, null is returned.
      *
-     * @param int $decimals The number of decimals numbers that should be printed
+     * @param  int  $decimals The number of decimals numbers that should be printed
      *
      * @return string|null A string like 1.3M
      */
-    public function getHumanFileSize(Attachment $attachment, $decimals = 2): ?string
+    public function getHumanFileSize(Attachment $attachment, int $decimals = 2): ?string
     {
         $bytes = $this->getFileSize($attachment);
 
diff --git a/src/Services/CustomEnvVarProcessor.php b/src/Services/CustomEnvVarProcessor.php
index 62f32c11..cd8e3c7e 100644
--- a/src/Services/CustomEnvVarProcessor.php
+++ b/src/Services/CustomEnvVarProcessor.php
@@ -48,7 +48,7 @@ use Symfony\Component\DependencyInjection\Exception\EnvNotFoundException;
 
 final class CustomEnvVarProcessor implements EnvVarProcessorInterface
 {
-    public function getEnv($prefix, $name, Closure $getEnv)
+    public function getEnv($prefix, $name, Closure $getEnv): bool
     {
         if ('validMailDSN' === $prefix) {
             try {
diff --git a/src/Services/EntityImporter.php b/src/Services/EntityImporter.php
index 7f214900..577282c5 100644
--- a/src/Services/EntityImporter.php
+++ b/src/Services/EntityImporter.php
@@ -228,9 +228,9 @@ class EntityImporter
      * This functions corrects the parent setting based on the children value of the parent.
      *
      * @param iterable                         $entities the list of entities that should be fixed
-     * @param AbstractStructuralDBElement|null $parent   the parent, to which the entity should be set
+     * @param  AbstractStructuralDBElement|null  $parent   the parent, to which the entity should be set
      */
-    protected function correctParentEntites(iterable $entities, $parent = null): void
+    protected function correctParentEntites(iterable $entities, AbstractStructuralDBElement $parent = null): void
     {
         foreach ($entities as $entity) {
             /** @var AbstractStructuralDBElement $entity */
diff --git a/src/Services/MoneyFormatter.php b/src/Services/MoneyFormatter.php
index b3c0e2c3..ca3e70c3 100644
--- a/src/Services/MoneyFormatter.php
+++ b/src/Services/MoneyFormatter.php
@@ -62,10 +62,10 @@ class MoneyFormatter
      *
      * @param string|float  $value           the value that should be formatted
      * @param Currency|null $currency        The currency that should be used for formatting. If null the global one is used
-     * @param int           $decimals        the number of decimals that should be shown
+     * @param  int  $decimals        the number of decimals that should be shown
      * @param bool          $show_all_digits if set to true, all digits are shown, even if they are null
      */
-    public function format($value, ?Currency $currency = null, $decimals = 5, bool $show_all_digits = false): string
+    public function format($value, ?Currency $currency = null, int $decimals = 5, bool $show_all_digits = false): string
     {
         $iso_code = $this->base_currency;
         if (null !== $currency && !empty($currency->getIsoCode())) {
diff --git a/src/Services/StructuralElementRecursionHelper.php b/src/Services/StructuralElementRecursionHelper.php
index 140c696f..1b04717c 100644
--- a/src/Services/StructuralElementRecursionHelper.php
+++ b/src/Services/StructuralElementRecursionHelper.php
@@ -62,10 +62,10 @@ class StructuralElementRecursionHelper
      *                                                      $func has the signature function(StructuralDBElement $element) : void
      * @param int                         $max_depth        The maximum depth for which should be recursivly called. So if this is set to 5, after the
      *                                                      5th level the execution is stopped.
-     * @param bool                        $call_from_bottom If set to true the bottom elements (elements with high level) will be called first.
+     * @param  bool  $call_from_bottom If set to true the bottom elements (elements with high level) will be called first.
      *                                                      Set to false if you want to call the top elements first.
      */
-    public function execute(AbstractStructuralDBElement $element, callable $func, int $max_depth = -1, $call_from_bottom = true): void
+    public function execute(AbstractStructuralDBElement $element, callable $func, int $max_depth = -1, bool $call_from_bottom = true): void
     {
         //Cancel if we reached our maximal allowed level. Must be zero because -1 is infinity levels
         if (0 === $max_depth) {
diff --git a/src/Services/TranslationExtractor/PermissionExtractor.php b/src/Services/TranslationExtractor/PermissionExtractor.php
index 8010fac8..f5605fdf 100644
--- a/src/Services/TranslationExtractor/PermissionExtractor.php
+++ b/src/Services/TranslationExtractor/PermissionExtractor.php
@@ -103,9 +103,9 @@ final class PermissionExtractor implements ExtractorInterface
     /**
      * Sets the prefix that should be used for new found messages.
      *
-     * @param string $prefix The prefix
+     * @param  string  $prefix The prefix
      */
-    public function setPrefix($prefix)
+    public function setPrefix(string $prefix): string
     {
         return '';
     }
diff --git a/src/Twig/AppExtension.php b/src/Twig/AppExtension.php
index 5e6585d6..5f021546 100644
--- a/src/Twig/AppExtension.php
+++ b/src/Twig/AppExtension.php
@@ -93,7 +93,7 @@ class AppExtension extends AbstractExtension
         $this->translator = $translator;
     }
 
-    public function getFilters()
+    public function getFilters(): array
     {
         return [
             new TwigFilter('entityURL', [$this, 'generateEntityURL']),
@@ -108,7 +108,7 @@ class AppExtension extends AbstractExtension
         ];
     }
 
-    public function getTests()
+    public function getTests(): array
     {
         return [
             new TwigTest('instanceof', static function ($var, $instance) {
@@ -117,7 +117,7 @@ class AppExtension extends AbstractExtension
         ];
     }
 
-    public function getFunctions()
+    public function getFunctions(): array
     {
         return [
             new TwigFunction('generateTreeData', [$this, 'treeData']),
diff --git a/src/Twig/BarcodeExtension.php b/src/Twig/BarcodeExtension.php
index 5a4fa88e..b61b874e 100644
--- a/src/Twig/BarcodeExtension.php
+++ b/src/Twig/BarcodeExtension.php
@@ -26,7 +26,7 @@ use Twig\TwigFilter;
 
 class BarcodeExtension extends AbstractExtension
 {
-    public function getFilters()
+    public function getFilters(): array
     {
         return [
             new TwigFilter('barcodeSVG', static function (string $content, string $type = 'QRCODE') {
diff --git a/src/Twig/LastUserExtension.php b/src/Twig/LastUserExtension.php
index 1d9a5fd3..159909ed 100644
--- a/src/Twig/LastUserExtension.php
+++ b/src/Twig/LastUserExtension.php
@@ -38,7 +38,7 @@ class LastUserExtension extends AbstractExtension
         $this->repo = $em->getRepository(AbstractLogEntry::class);
     }
 
-    public function getFunctions()
+    public function getFunctions(): array
     {
         return [
             new TwigFunction('getLastEditingUser', [$this->repo, 'getLastEditingUser']),
diff --git a/src/Validator/Constraints/BigDecimal/BigDecimalGreaterThanValidator.php b/src/Validator/Constraints/BigDecimal/BigDecimalGreaterThanValidator.php
index 49d15fb8..12962142 100644
--- a/src/Validator/Constraints/BigDecimal/BigDecimalGreaterThanValidator.php
+++ b/src/Validator/Constraints/BigDecimal/BigDecimalGreaterThanValidator.php
@@ -35,7 +35,7 @@ class BigDecimalGreaterThanValidator extends AbstractComparisonValidator
     /**
      * {@inheritdoc}
      */
-    protected function compareValues($value1, $value2)
+    protected function compareValues($value1, $value2): bool
     {
         if ($value1 instanceof BigDecimal) {
             $value1 = (string) $value1;
@@ -51,7 +51,7 @@ class BigDecimalGreaterThanValidator extends AbstractComparisonValidator
     /**
      * {@inheritdoc}
      */
-    protected function getErrorCode()
+    protected function getErrorCode(): ?string
     {
         return GreaterThan::TOO_LOW_ERROR;
     }
diff --git a/src/Validator/Constraints/BigDecimal/BigDecimalGreaterThenOrEqualValidator.php b/src/Validator/Constraints/BigDecimal/BigDecimalGreaterThenOrEqualValidator.php
index bc88027b..f889e0ae 100644
--- a/src/Validator/Constraints/BigDecimal/BigDecimalGreaterThenOrEqualValidator.php
+++ b/src/Validator/Constraints/BigDecimal/BigDecimalGreaterThenOrEqualValidator.php
@@ -35,7 +35,7 @@ class BigDecimalGreaterThenOrEqualValidator extends AbstractComparisonValidator
     /**
      * {@inheritdoc}
      */
-    protected function compareValues($value1, $value2)
+    protected function compareValues($value1, $value2): bool
     {
         if ($value1 instanceof BigDecimal) {
             $value1 = (string) $value1;
@@ -51,7 +51,7 @@ class BigDecimalGreaterThenOrEqualValidator extends AbstractComparisonValidator
     /**
      * {@inheritdoc}
      */
-    protected function getErrorCode()
+    protected function getErrorCode(): ?string
     {
         return GreaterThanOrEqual::TOO_LOW_ERROR;
     }
diff --git a/src/Validator/Constraints/ValidPartLot.php b/src/Validator/Constraints/ValidPartLot.php
index 2cf1de97..97605e31 100644
--- a/src/Validator/Constraints/ValidPartLot.php
+++ b/src/Validator/Constraints/ValidPartLot.php
@@ -52,7 +52,7 @@ use Symfony\Component\Validator\Constraint;
  */
 class ValidPartLot extends Constraint
 {
-    public function getTargets()
+    public function getTargets(): string
     {
         return self::CLASS_CONSTRAINT;
     }
diff --git a/tests/Services/Attachments/AttachmentPathResolverTest.php b/tests/Services/Attachments/AttachmentPathResolverTest.php
index 78387882..5a0d61a0 100644
--- a/tests/Services/Attachments/AttachmentPathResolverTest.php
+++ b/tests/Services/Attachments/AttachmentPathResolverTest.php
@@ -49,61 +49,63 @@ use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
 
 class AttachmentPathResolverTest extends WebTestCase
 {
-    public static $media_path;
-    public static $footprint_path;
-    protected static $projectDir_orig;
-    protected static $projectDir;
+    protected $media_path;
+    protected $footprint_path;
+    protected $projectDir_orig;
+    protected $projectDir;
     /**
      * @var AmountFormatter
      */
-    protected static $service;
+    protected $service;
 
-    public function __construct($name = null, array $data = [], $dataName = '')
+    public function setUp(): void
     {
-        parent::__construct($name, $data, $dataName);
-
-        self::bootKernel();
-        self::$projectDir_orig = realpath(self::$kernel->getProjectDir());
-        self::$projectDir = str_replace('\\', '/', self::$projectDir_orig);
-        self::$media_path = self::$projectDir.'/public/media';
-        self::$footprint_path = self::$projectDir.'/public/img/footprints';
-    }
-
-    public static function setUpBeforeClass(): void
-    {
-        parent::setUpBeforeClass();
+        parent::setUp();
 
         //Get an service instance.
         self::bootKernel();
-        self::$service = self::$container->get(AttachmentPathResolver::class);
+
+        $this->projectDir_orig = realpath(self::$kernel->getProjectDir());
+        $this->projectDir = str_replace('\\', '/', $this->projectDir_orig);
+        $this->media_path = $this->projectDir.'/public/media';
+        $this->footprint_path = $this->projectDir.'/public/img/footprints';
+
+        $this->service = self::getContainer()->get(AttachmentPathResolver::class);
     }
 
     public function testParameterToAbsolutePath(): void
     {
         //If null is passed, null must be returned
-        $this->assertNull(self::$service->parameterToAbsolutePath(null));
+        $this->assertNull($this->service->parameterToAbsolutePath(null));
 
         //Absolute path should be returned like they are (we use projectDir here, because we know that this dir exists)
-        $this->assertSame(self::$projectDir_orig, self::$service->parameterToAbsolutePath(self::$projectDir));
+        $this->assertSame($this->projectDir_orig, $this->service->parameterToAbsolutePath($this->projectDir));
 
         //Relative pathes should be resolved
-        $expected = str_replace('\\', '/', self::$projectDir_orig.DIRECTORY_SEPARATOR.'src');
-        $this->assertSame($expected, self::$service->parameterToAbsolutePath('src'));
-        $this->assertSame($expected, self::$service->parameterToAbsolutePath('./src'));
+        $expected = str_replace('\\', '/', $this->projectDir_orig.DIRECTORY_SEPARATOR.'src');
+        $this->assertSame($expected, $this->service->parameterToAbsolutePath('src'));
+        $this->assertSame($expected, $this->service->parameterToAbsolutePath('./src'));
 
         //Invalid pathes should return null
-        $this->assertNull(self::$service->parameterToAbsolutePath('/this/path/does/not/exist'));
-        $this->assertNull(self::$service->parameterToAbsolutePath('/./this/one/too'));
+        $this->assertNull($this->service->parameterToAbsolutePath('/this/path/does/not/exist'));
+        $this->assertNull($this->service->parameterToAbsolutePath('/./this/one/too'));
     }
 
     public function placeholderDataProvider(): array
     {
+        //We need to do initialization (again), as dataprovider is called before setUp()
+        self::bootKernel();
+        $this->projectDir_orig = realpath(self::$kernel->getProjectDir());
+        $this->projectDir = str_replace('\\', '/', $this->projectDir_orig);
+        $this->media_path = $this->projectDir.'/public/media';
+        $this->footprint_path = $this->projectDir.'/public/img/footprints';
+
         return [
-            ['%FOOTPRINTS%/test/test.jpg', self::$footprint_path.'/test/test.jpg'],
-            ['%FOOTPRINTS%/test/', self::$footprint_path.'/test/'],
-            ['%MEDIA%/test', self::$media_path.'/test'],
-            ['%MEDIA%', self::$media_path],
-            ['%FOOTPRINTS%', self::$footprint_path],
+            ['%FOOTPRINTS%/test/test.jpg', $this->footprint_path.'/test/test.jpg'],
+            ['%FOOTPRINTS%/test/', $this->footprint_path.'/test/'],
+            ['%MEDIA%/test', $this->media_path.'/test'],
+            ['%MEDIA%', $this->media_path],
+            ['%FOOTPRINTS%', $this->footprint_path],
             //Footprints 3D are disabled
             ['%FOOTPRINTS_3D%', null],
             //Check that invalid pathes return null
@@ -120,18 +122,25 @@ class AttachmentPathResolverTest extends WebTestCase
 
     public function realPathDataProvider(): array
     {
+        //We need to do initialization (again), as dataprovider is called before setUp()
+        self::bootKernel();
+        $this->projectDir_orig = realpath(self::$kernel->getProjectDir());
+        $this->projectDir = str_replace('\\', '/', $this->projectDir_orig);
+        $this->media_path = $this->projectDir.'/public/media';
+        $this->footprint_path = $this->projectDir.'/public/img/footprints';
+
         return [
-            [self::$media_path.'/test/img.jpg', '%MEDIA%/test/img.jpg'],
-            [self::$media_path.'/test/img.jpg', '%BASE%/data/media/test/img.jpg', true],
-            [self::$footprint_path.'/foo.jpg', '%FOOTPRINTS%/foo.jpg'],
-            [self::$footprint_path.'/foo.jpg', '%FOOTPRINTS%/foo.jpg', true],
+            [$this->media_path.'/test/img.jpg', '%MEDIA%/test/img.jpg'],
+            [$this->media_path.'/test/img.jpg', '%BASE%/data/media/test/img.jpg', true],
+            [$this->footprint_path.'/foo.jpg', '%FOOTPRINTS%/foo.jpg'],
+            [$this->footprint_path.'/foo.jpg', '%FOOTPRINTS%/foo.jpg', true],
             //Every kind of absolute path, that is not based with our placeholder dirs must be invald
             ['/etc/passwd', null],
             ['C:\\not\\existing.txt', null],
             //More then one placeholder is not allowed
-            [self::$footprint_path.'/test/'.self::$footprint_path, null],
+            [$this->footprint_path.'/test/'.$this->footprint_path, null],
             //Path must begin with path
-            ['/not/root'.self::$footprint_path, null],
+            ['/not/root'.$this->footprint_path, null],
         ];
     }
 
@@ -140,7 +149,7 @@ class AttachmentPathResolverTest extends WebTestCase
      */
     public function testPlaceholderToRealPath($param, $expected): void
     {
-        $this->assertSame($expected, self::$service->placeholderToRealPath($param));
+        $this->assertSame($expected, $this->service->placeholderToRealPath($param));
     }
 
     /**
@@ -148,6 +157,6 @@ class AttachmentPathResolverTest extends WebTestCase
      */
     public function testRealPathToPlaceholder($param, $expected, $old_method = false): void
     {
-        $this->assertSame($expected, self::$service->realPathToPlaceholder($param, $old_method));
+        $this->assertSame($expected, $this->service->realPathToPlaceholder($param, $old_method));
     }
 }