diff --git a/modules/jsonapi_defaults/src/Controller/EntityResource.php b/modules/jsonapi_defaults/src/Controller/EntityResource.php
index cffff95..8e855b5 100644
--- a/modules/jsonapi_defaults/src/Controller/EntityResource.php
+++ b/modules/jsonapi_defaults/src/Controller/EntityResource.php
@@ -30,7 +30,7 @@ class EntityResource extends JsonApiEntityResourse {
       $resource_type = static::correctResourceTypeOnRelated($related_field, $resource_type);
     }
     catch (\LengthException $e) {
-      watchdog_exception('jsonapi_defaults', $e);
+      \Drupal\Component\Utility\DeprecationHelper::backwardsCompatibleCall(\Drupal::VERSION, '10.1.0', fn() => \Drupal\Core\Utility\Error::logException(\Drupal::logger('jsonapi_defaults'), $e), fn() => watchdog_exception('jsonapi_defaults', $e));
       $resource_type = NULL;
     }
 
@@ -110,7 +110,7 @@ class EntityResource extends JsonApiEntityResourse {
         $resource_type = static::correctResourceTypeOnRelated($request->get('related'), $resource_type);
       }
       catch (\LengthException $e) {
-        watchdog_exception('jsonapi_defaults', $e);
+        \Drupal\Component\Utility\DeprecationHelper::backwardsCompatibleCall(\Drupal::VERSION, '10.1.0', fn() => \Drupal\Core\Utility\Error::logException(\Drupal::logger('jsonapi_defaults'), $e), fn() => watchdog_exception('jsonapi_defaults', $e));
         return parent::getIncludes($request, $data);
       }
       if (!$resource_type instanceof ConfigurableResourceType) {
diff --git a/src/EventSubscriber/ConfigSubscriber.php b/src/EventSubscriber/ConfigSubscriber.php
index 10c7ffe..c4bf7dd 100644
--- a/src/EventSubscriber/ConfigSubscriber.php
+++ b/src/EventSubscriber/ConfigSubscriber.php
@@ -103,7 +103,7 @@ class ConfigSubscriber implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     $events[ConfigEvents::SAVE][] = ['onSave'];
     // Run before
     // \Drupal\jsonapi\EventSubscriber\ResourceResponseSubscriber::onResponse()
diff --git a/src/EventSubscriber/JsonApiBuildSubscriber.php b/src/EventSubscriber/JsonApiBuildSubscriber.php
index ef62628..0261e1b 100644
--- a/src/EventSubscriber/JsonApiBuildSubscriber.php
+++ b/src/EventSubscriber/JsonApiBuildSubscriber.php
@@ -50,7 +50,7 @@ class JsonApiBuildSubscriber implements EventSubscriberInterface {
   /**
    * What events to subscribe to.
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     $events[ResourceTypeBuildEvents::BUILD][] = ['applyResourceConfig'];
     return $events;
   }
diff --git a/src/Form/JsonapiResourceConfigForm.php b/src/Form/JsonapiResourceConfigForm.php
index b9e5f47..d08871e 100644
--- a/src/Form/JsonapiResourceConfigForm.php
+++ b/src/Form/JsonapiResourceConfigForm.php
@@ -170,7 +170,7 @@ class JsonapiResourceConfigForm extends EntityForm {
       }
       catch (PluginNotFoundException $exception) {
         // Log the exception and continue.
-        watchdog_exception('jsonapi_extras', $exception);
+        \Drupal\Component\Utility\DeprecationHelper::backwardsCompatibleCall(\Drupal::VERSION, '10.1.0', fn() => \Drupal\Core\Utility\Error::logException(\Drupal::logger('jsonapi_extras'), $exception), fn() => watchdog_exception('jsonapi_extras', $exception));
       }
       $form['id'] = ['#type' => 'hidden', '#value' => $resource_config_id];
     }
@@ -340,7 +340,7 @@ class JsonapiResourceConfigForm extends EntityForm {
       }
       catch (PluginException $exception) {
         // Log exception and continue.
-        watchdog_exception('jsonapi_extras', $exception);
+        \Drupal\Component\Utility\DeprecationHelper::backwardsCompatibleCall(\Drupal::VERSION, '10.1.0', fn() => \Drupal\Core\Utility\Error::logException(\Drupal::logger('jsonapi_extras'), $exception), fn() => watchdog_exception('jsonapi_extras', $exception));
         continue;
       }
       NestedArray::setValue(
diff --git a/src/Normalizer/FieldItemNormalizer.php b/src/Normalizer/FieldItemNormalizer.php
index 8882870..6d216ba 100644
--- a/src/Normalizer/FieldItemNormalizer.php
+++ b/src/Normalizer/FieldItemNormalizer.php
@@ -48,7 +48,7 @@ class FieldItemNormalizer extends JsonApiNormalizerDecoratorBase {
   /**
    * {@inheritdoc}
    */
-  public function normalize($object, $format = NULL, array $context = []) {
+  public function normalize($object, $format = NULL, array $context = []): array|bool|string|int|float|null|\ArrayObject {
     // First get the regular output.
     $normalized_output = parent::normalize($object, $format, $context);
     // Then detect if there is any enhancer to be applied here.
diff --git a/src/Normalizer/JsonApiNormalizerDecoratorBase.php b/src/Normalizer/JsonApiNormalizerDecoratorBase.php
index eec01e5..bb803b7 100644
--- a/src/Normalizer/JsonApiNormalizerDecoratorBase.php
+++ b/src/Normalizer/JsonApiNormalizerDecoratorBase.php
@@ -34,7 +34,7 @@ class JsonApiNormalizerDecoratorBase implements NormalizerInterface, Denormalize
   /**
    * {@inheritdoc}
    */
-  public function normalize($object, $format = NULL, array $context = []) {
+  public function normalize($object, $format = NULL, array $context = []): array|bool|string|int|float|null|\ArrayObject {
     return $this->inner->normalize($object, $format, $context);
   }
 
@@ -55,14 +55,14 @@ class JsonApiNormalizerDecoratorBase implements NormalizerInterface, Denormalize
   /**
    * {@inheritdoc}
    */
-  public function supportsNormalization($data, $format = NULL) {
+  public function supportsNormalization($data, $format = NULL): bool {
     return $this->inner instanceof NormalizerInterface && $this->inner->supportsNormalization($data, $format);
   }
 
   /**
    * {@inheritdoc}
    */
-  public function supportsDenormalization($data, $type, $format = NULL) {
+  public function supportsDenormalization($data, $type, $format = NULL): bool {
     return $this->inner instanceof DenormalizerInterface && $this->inner->supportsDenormalization($data, $type, $format);
   }
 
diff --git a/src/Normalizer/ResourceIdentifierNormalizer.php b/src/Normalizer/ResourceIdentifierNormalizer.php
index c6a7cf6..aa761f1 100644
--- a/src/Normalizer/ResourceIdentifierNormalizer.php
+++ b/src/Normalizer/ResourceIdentifierNormalizer.php
@@ -43,7 +43,7 @@ class ResourceIdentifierNormalizer extends JsonApiNormalizerDecoratorBase {
   /**
    * {@inheritdoc}
    */
-  public function normalize($field, $format = NULL, array $context = []) {
+  public function normalize($field, $format = NULL, array $context = []): array|bool|string|int|float|null|\ArrayObject {
     assert($field instanceof ResourceIdentifier);
     $normalized_output = parent::normalize($field, $format, $context);
     assert($normalized_output instanceof CacheableNormalization);
diff --git a/src/Normalizer/ResourceObjectNormalizer.php b/src/Normalizer/ResourceObjectNormalizer.php
index edec9aa..6f84de3 100644
--- a/src/Normalizer/ResourceObjectNormalizer.php
+++ b/src/Normalizer/ResourceObjectNormalizer.php
@@ -18,7 +18,7 @@ class ResourceObjectNormalizer extends JsonApiNormalizerDecoratorBase {
   /**
    * {@inheritdoc}
    */
-  public function normalize($object, $format = NULL, array $context = []) {
+  public function normalize($object, $format = NULL, array $context = []): array|bool|string|int|float|null|\ArrayObject {
     assert($object instanceof ResourceObject);
     $resource_type = $object->getResourceType();
     $cacheable_normalization = parent::normalize($object, $format, $context);
diff --git a/src/SerializerDecorator.php b/src/SerializerDecorator.php
index 4a5c157..cc78076 100644
--- a/src/SerializerDecorator.php
+++ b/src/SerializerDecorator.php
@@ -98,14 +98,14 @@ class SerializerDecorator implements SerializerInterface, NormalizerInterface, D
   /**
    * {@inheritdoc}
    */
-  public function normalize($object, $format = NULL, array $context = []) {
+  public function normalize($object, $format = NULL, array $context = []): array|bool|string|int|float|null|\ArrayObject {
     return $this->relay(__FUNCTION__, func_get_args());
   }
 
   /**
    * {@inheritdoc}
    */
-  public function supportsDecoding($format) {
+  public function supportsDecoding($format): bool {
     return $this->relay(__FUNCTION__, func_get_args());
   }
 
@@ -119,7 +119,7 @@ class SerializerDecorator implements SerializerInterface, NormalizerInterface, D
   /**
    * {@inheritdoc}
    */
-  public function supportsDenormalization($data, $type, $format = NULL) {
+  public function supportsDenormalization($data, $type, $format = NULL): bool {
     return $this->relay(__FUNCTION__, func_get_args());
   }
 
@@ -133,7 +133,7 @@ class SerializerDecorator implements SerializerInterface, NormalizerInterface, D
   /**
    * {@inheritdoc}
    */
-  public function supportsNormalization($data, $format = NULL) {
+  public function supportsNormalization($data, $format = NULL): bool {
     return $this->relay(__FUNCTION__, func_get_args());
   }