diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index e41b5000dd58bdda98e8636ddc636dd123cace63..70333a38894af6664266e601e071f8dc662f8579 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -51,6 +51,7 @@ variables:
   CORE_PREVIOUS_PHP_MIN: 8.0
   OPT_IN_TEST_PREVIOUS_MINOR: 1
   OPT_IN_TEST_NEXT_MINOR: 1
+  OPT_IN_TEST_NEXT_MAJOR: 1
 
 
 ###################################################################################
diff --git a/jsonapi_resources.info.yml b/jsonapi_resources.info.yml
index eac9600772e4daddd5847c6c82324c5fef77e2ab..f8a623ea9b8a2db123085418091a31a7345944d0 100644
--- a/jsonapi_resources.info.yml
+++ b/jsonapi_resources.info.yml
@@ -1,6 +1,6 @@
 name: 'JSON:API Resources'
 description: "This module let's you define custom resources at routes of your choice that use existing resource types."
-core_version_requirement: ^9.1 || ^10
+core_version_requirement: ^9.1 || ^10 || ^11
 type: module
 dependencies:
   - drupal:jsonapi
diff --git a/tests/modules/jsonapi_resources_test/jsonapi_resources_test.info.yml b/tests/modules/jsonapi_resources_test/jsonapi_resources_test.info.yml
index 45422e6459f2c30af8fda8cc0b275aa542fb5af1..4de1df32ce756991d65acb4424feb6a2e7d673b5 100644
--- a/tests/modules/jsonapi_resources_test/jsonapi_resources_test.info.yml
+++ b/tests/modules/jsonapi_resources_test/jsonapi_resources_test.info.yml
@@ -2,6 +2,7 @@ name: 'JSON:API Resources test module'
 description: "Tests for JSON:API Resources."
 type: module
 package: Testing
+core_version_requirement: ^9.1 || ^10 || ^11
 dependencies:
   - drupal:node
   - jsonapi_resources:jsonapi_resources
diff --git a/tests/src/Functional/JsonapiResourceTest.php b/tests/src/Functional/JsonapiResourceTest.php
index aa9c712c9e6fcfb969f7053917ac14653b755913..44a6fcc1a0bbcac3399f169e9ac3db4c02b653a8 100644
--- a/tests/src/Functional/JsonapiResourceTest.php
+++ b/tests/src/Functional/JsonapiResourceTest.php
@@ -10,7 +10,7 @@ use Drupal\Core\Url;
 use Drupal\node\Entity\Node;
 use Drupal\node\Entity\NodeType;
 use Drupal\Tests\BrowserTestBase;
-use Drupal\Tests\field\Traits\EntityReferenceTestTrait;
+use Drupal\Tests\field\Traits\EntityReferenceFieldCreationTrait;
 use Drupal\Tests\jsonapi\Functional\JsonApiRequestTestTrait;
 use Drupal\Tests\jsonapi\Functional\ResourceResponseTestTrait;
 use Drupal\user\Entity\Role;
@@ -18,6 +18,12 @@ use Drupal\user\Entity\User;
 use Drupal\user\RoleInterface;
 use GuzzleHttp\RequestOptions;
 
+// Workaround to support tests against Drupal 9, 10 and 11.
+// @todo Remove once we end support for Drupal 10.1.x and below.
+if (!trait_exists(EntityReferenceFieldCreationTrait::class)) {
+  class_alias('\Drupal\Tests\field\Traits\EntityReferenceTestTrait', EntityReferenceFieldCreationTrait::class);
+}
+
 /**
  * Tests JSON:API Resource processors.
  *
@@ -27,7 +33,7 @@ class JsonapiResourceTest extends BrowserTestBase {
 
   use JsonApiRequestTestTrait;
   use ResourceResponseTestTrait;
-  use EntityReferenceTestTrait;
+  use EntityReferenceFieldCreationTrait;
   use CommentTestTrait;
 
   /**
diff --git a/tests/src/Kernel/ResourceResponseFactoryTest.php b/tests/src/Kernel/ResourceResponseFactoryTest.php
index 77f34ac24ba7d5bc87500c569e70c596af763035..19edc9a1a64cfa0a391f557feeb7d6dfb1a7bef8 100644
--- a/tests/src/Kernel/ResourceResponseFactoryTest.php
+++ b/tests/src/Kernel/ResourceResponseFactoryTest.php
@@ -14,10 +14,16 @@ use Drupal\jsonapi\ResourceType\ResourceTypeRepositoryInterface;
 use Drupal\KernelTests\KernelTestBase;
 use Drupal\node\Entity\Node;
 use Drupal\node\Entity\NodeType;
-use Drupal\Tests\field\Traits\EntityReferenceTestTrait;
+use Drupal\Tests\field\Traits\EntityReferenceFieldCreationTrait;
 use Drupal\Tests\user\Traits\UserCreationTrait;
 use Symfony\Component\HttpFoundation\Request;
 
+// Workaround to support tests against Drupal 9, 10 and 11.
+// @todo Remove once we end support for Drupal 10.1.x and below.
+if (!trait_exists(EntityReferenceFieldCreationTrait::class)) {
+  class_alias('\Drupal\Tests\field\Traits\EntityReferenceTestTrait', EntityReferenceFieldCreationTrait::class);
+}
+
 /**
  * Tests ResourceResponseFactory.
  *
@@ -26,7 +32,7 @@ use Symfony\Component\HttpFoundation\Request;
  */
 final class ResourceResponseFactoryTest extends KernelTestBase {
 
-  use EntityReferenceTestTrait;
+  use EntityReferenceFieldCreationTrait;
   use UserCreationTrait;
 
   private const NODE_TYPE_ARTICLE_UUID = 'e5da5021-d7a0-4606-a21c-9586a8cf79a4';
diff --git a/tests/src/Unit/Routing/ResourceRoutesTest.php b/tests/src/Unit/Routing/ResourceRoutesTest.php
index cd986163f9ad6599907ddaa8bdac92b6d02186dd..2972360bc269fa02304d76790039df6655ed4c64 100644
--- a/tests/src/Unit/Routing/ResourceRoutesTest.php
+++ b/tests/src/Unit/Routing/ResourceRoutesTest.php
@@ -35,7 +35,15 @@ final class ResourceRoutesTest extends UnitTestCase {
       '_jsonapi_resource_types' => ['node--article'],
     ];
     $route_collection->add('jsonapi_resource_route', new Route('/%jsonapi%/resource', $route_defaults));
-    $route_collection->add('jsonapi_resource_multi_method_route', new Route('/%jsonapi%/resource', $route_defaults, [], [], '', [], ['POST', 'PATCH']));
+    $route_collection->add('jsonapi_resource_multi_method_route', new Route(
+      '/%jsonapi%/resource',
+      $route_defaults,
+      [],
+      [],
+      '',
+      [],
+      ['POST', 'PATCH'],
+    ));
 
     $route_rebuild_event = new RouteBuildEvent($route_collection);