diff --git a/core/misc/cspell/dictionary.txt b/core/misc/cspell/dictionary.txt
index d492ebe27a..7a7a6b7f30 100644
--- a/core/misc/cspell/dictionary.txt
+++ b/core/misc/cspell/dictionary.txt
@@ -1825,6 +1825,7 @@ unsets
 unsetting
 unshortened
 unsimplified
+unskip
 unsticky
 unstripped
 unsynchronized
diff --git a/core/modules/jsonapi/src/ResourceType/ResourceTypeRepository.php b/core/modules/jsonapi/src/ResourceType/ResourceTypeRepository.php
index c2d306d4b9..fe508b9708 100644
--- a/core/modules/jsonapi/src/ResourceType/ResourceTypeRepository.php
+++ b/core/modules/jsonapi/src/ResourceType/ResourceTypeRepository.php
@@ -14,6 +14,7 @@
 use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Entity\FieldableEntityInterface;
 use Drupal\Core\Field\FieldDefinitionInterface;
+use Drupal\Core\Installer\InstallerKernel;
 use Drupal\Core\TypedData\DataReferenceTargetDefinition;
 use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\HttpKernel\Exception\PreconditionFailedHttpException;
@@ -179,7 +180,7 @@ public function get($entity_type_id, $bundle) {
       throw new PreconditionFailedHttpException('Server error. The current route is malformed.');
     }
 
-    return $this->getByTypeName("$entity_type_id--$bundle");
+    return static::lookupResourceType($this->all(), $entity_type_id, $bundle);
   }
 
   /**
@@ -423,19 +424,34 @@ protected function calculateRelatableResourceTypes(ResourceType $resource_type,
    */
   protected function getRelatableResourceTypesFromFieldDefinition(FieldDefinitionInterface $field_definition, array $resource_types) {
     $item_definition = $field_definition->getItemDefinition();
-
     $entity_type_id = $item_definition->getSetting('target_type');
     $handler_settings = $item_definition->getSetting('handler_settings');
+    $target_bundles = empty($handler_settings['target_bundles']) ? $this->getAllBundlesForEntityType($entity_type_id) : $handler_settings['target_bundles'];
+    $relatable_resource_types = [];
 
-    $has_target_bundles = isset($handler_settings['target_bundles']) && !empty($handler_settings['target_bundles']);
-    $target_bundles = $has_target_bundles ?
-      $handler_settings['target_bundles']
-      : $this->getAllBundlesForEntityType($entity_type_id);
+    foreach ($target_bundles as $target_bundle) {
+      if ($resource_type = static::lookupResourceType($resource_types, $entity_type_id, $target_bundle)) {
+        $relatable_resource_types[] = $resource_type;
+      }
+      // Do not warn during the site installation since system integrity
+      // is not guaranteed in this period and the warnings may pop up falsy,
+      // adding confusion to the process.
+      elseif (!InstallerKernel::installationAttempted()) {
+        trigger_error(
+          sprintf(
+            'The "%s" at "%s:%s" references the "%s:%s" entity type that does not exist. Please take action.',
+            $field_definition->getName(),
+            $field_definition->getTargetEntityTypeId(),
+            $field_definition->getTargetBundle(),
+            $entity_type_id,
+            $target_bundle
+          ),
+          E_USER_WARNING
+        );
+      }
+    }
 
-    return array_map(function ($target_bundle) use ($entity_type_id, $resource_types) {
-      $type_name = "$entity_type_id--$target_bundle";
-      return isset($resource_types[$type_name]) ? $resource_types[$type_name] : NULL;
-    }, $target_bundles);
+    return $relatable_resource_types;
   }
 
   /**
@@ -473,7 +489,36 @@ protected function isReferenceFieldDefinition(FieldDefinitionInterface $field_de
    *   The bundle IDs.
    */
   protected function getAllBundlesForEntityType($entity_type_id) {
-    return array_keys($this->entityTypeBundleInfo->getBundleInfo($entity_type_id));
+    // Ensure all keys are strings because numeric values are allowed as bundle
+    // names and "array_keys()" casts "42" to 42.
+    return array_map('strval', array_keys($this->entityTypeBundleInfo->getBundleInfo($entity_type_id)));
+  }
+
+  /**
+   * Lookup a resource type by entity type ID and bundle name.
+   *
+   * @param \Drupal\jsonapi\ResourceType\ResourceType[] $resource_types
+   *   The list of resource types to do a lookup.
+   * @param string $entity_type_id
+   *   The entity type of a seekable resource type.
+   * @param string $bundle
+   *   The entity bundle of a seekable resource type.
+   *
+   * @return \Drupal\jsonapi\ResourceType\ResourceType|null
+   *   The resource type or NULL if one cannot be found.
+   */
+  protected static function lookupResourceType(array $resource_types, $entity_type_id, $bundle) {
+    if (isset($resource_types["$entity_type_id--$bundle"])) {
+      return $resource_types["$entity_type_id--$bundle"];
+    }
+
+    foreach ($resource_types as $resource_type) {
+      if ($resource_type->getEntityTypeId() === $entity_type_id && $resource_type->getBundle() === $bundle) {
+        return $resource_type;
+      }
+    }
+
+    return NULL;
   }
 
 }
diff --git a/core/modules/jsonapi/tests/modules/jsonapi_test_resource_type_aliasing/jsonapi_test_resource_type_aliasing.info.yml b/core/modules/jsonapi/tests/modules/jsonapi_test_resource_type_aliasing/jsonapi_test_resource_type_aliasing.info.yml
new file mode 100644
index 0000000000..828588185d
--- /dev/null
+++ b/core/modules/jsonapi/tests/modules/jsonapi_test_resource_type_aliasing/jsonapi_test_resource_type_aliasing.info.yml
@@ -0,0 +1,3 @@
+name: 'JSON:API test resource type aliasing'
+type: module
+package: Testing
diff --git a/core/modules/jsonapi/tests/modules/jsonapi_test_resource_type_aliasing/jsonapi_test_resource_type_aliasing.services.yml b/core/modules/jsonapi/tests/modules/jsonapi_test_resource_type_aliasing/jsonapi_test_resource_type_aliasing.services.yml
new file mode 100644
index 0000000000..9c02e50e34
--- /dev/null
+++ b/core/modules/jsonapi/tests/modules/jsonapi_test_resource_type_aliasing/jsonapi_test_resource_type_aliasing.services.yml
@@ -0,0 +1,5 @@
+services:
+  Drupal\jsonapi_test_resource_type_aliasing\ResourceType\AliasingResourceTypeRepository:
+    decorates: jsonapi.resource_type.repository
+    parent: jsonapi.resource_type.repository
+    public: false
diff --git a/core/modules/jsonapi/tests/modules/jsonapi_test_resource_type_aliasing/src/ResourceType/AliasedResourceType.php b/core/modules/jsonapi/tests/modules/jsonapi_test_resource_type_aliasing/src/ResourceType/AliasedResourceType.php
new file mode 100644
index 0000000000..761dc8ee59
--- /dev/null
+++ b/core/modules/jsonapi/tests/modules/jsonapi_test_resource_type_aliasing/src/ResourceType/AliasedResourceType.php
@@ -0,0 +1,33 @@
+<?php
+
+namespace Drupal\jsonapi_test_resource_type_aliasing\ResourceType;
+
+use Drupal\jsonapi\ResourceType\ResourceType;
+use Drupal\jsonapi\ResourceType\ResourceType as ResourceTypeBase;
+
+/**
+ * Resource type with uses an alternative type name.
+ *
+ * @todo remove this class in https://www.drupal.org/project/drupal/issues/3105318
+ */
+class AliasedResourceType extends ResourceTypeBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function __construct(ResourceType $resource_type, string $alias) {
+    parent::__construct(
+      $resource_type->getEntityTypeId(),
+      $resource_type->getBundle(),
+      $resource_type->getDeserializationTargetClass(),
+      $resource_type->isInternal(),
+      $resource_type->isLocatable(),
+      $resource_type->isMutable(),
+      $resource_type->isVersionable(),
+      $resource_type->getFields()
+    );
+    // Alias the resource type name with an alternative pattern.
+    $this->typeName = $alias;
+  }
+
+}
diff --git a/core/modules/jsonapi/tests/modules/jsonapi_test_resource_type_aliasing/src/ResourceType/AliasingResourceTypeRepository.php b/core/modules/jsonapi/tests/modules/jsonapi_test_resource_type_aliasing/src/ResourceType/AliasingResourceTypeRepository.php
new file mode 100644
index 0000000000..6b8bc234db
--- /dev/null
+++ b/core/modules/jsonapi/tests/modules/jsonapi_test_resource_type_aliasing/src/ResourceType/AliasingResourceTypeRepository.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace Drupal\jsonapi_test_resource_type_aliasing\ResourceType;
+
+use Drupal\Core\Entity\EntityTypeInterface;
+use Drupal\jsonapi\ResourceType\ResourceTypeRepository as ResourceTypeRepositoryBase;
+
+/**
+ * Provides JSON:API resource types with a different type name pattern.
+ *
+ * @todo remove this class in https://www.drupal.org/project/drupal/issues/3105318
+ */
+class AliasingResourceTypeRepository extends ResourceTypeRepositoryBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function createResourceType(EntityTypeInterface $entity_type, $bundle) {
+    $alias = sprintf('%s==%s', $entity_type->id(), $bundle);
+    $base_resource_type = parent::createResourceType($entity_type, $bundle);
+    return new AliasedResourceType($base_resource_type, $alias);
+  }
+
+}
diff --git a/core/modules/jsonapi/tests/src/Kernel/ResourceType/RelatedResourceTypesTest.php b/core/modules/jsonapi/tests/src/Kernel/ResourceType/RelatedResourceTypesTest.php
index c8afcce764..3ee33a9c6e 100644
--- a/core/modules/jsonapi/tests/src/Kernel/ResourceType/RelatedResourceTypesTest.php
+++ b/core/modules/jsonapi/tests/src/Kernel/ResourceType/RelatedResourceTypesTest.php
@@ -4,6 +4,7 @@
 
 use Drupal\Tests\jsonapi\Kernel\JsonapiKernelTestBase;
 use Drupal\node\Entity\NodeType;
+use PHPUnit\Framework\Error\Warning;
 
 /**
  * @coversDefaultClass \Drupal\jsonapi\ResourceType\ResourceType
@@ -179,4 +180,35 @@ public function getRelatableResourceTypesByFieldProvider() {
     ];
   }
 
+  /**
+   * Ensure a graceful failure when a field can references a missing bundle.
+   *
+   * @covers \Drupal\jsonapi\ResourceType\ResourceTypeRepository::all
+   * @covers \Drupal\jsonapi\ResourceType\ResourceTypeRepository::calculateRelatableResourceTypes
+   * @covers \Drupal\jsonapi\ResourceType\ResourceTypeRepository::getRelatableResourceTypesFromFieldDefinition
+   *
+   * @link https://www.drupal.org/project/drupal/issues/2996114
+   */
+  public function testGetRelatableResourceTypesFromFieldDefinition() {
+    $field_config_storage = $this->container->get('entity_type.manager')->getStorage('field_config');
+
+    static::assertCount(0, $this->resourceTypeRepository->get('node', 'foo')->getRelatableResourceTypesByField('field_relationship'));
+    $this->createEntityReferenceField('node', 'foo', 'field_ref_with_missing_bundle', 'Related entity', 'node', 'default', [
+      'target_bundles' => ['missing_bundle'],
+    ]);
+    $fields = $field_config_storage->loadByProperties(['field_name' => 'field_ref_with_missing_bundle']);
+    static::assertSame(['missing_bundle'], $fields['node.foo.field_ref_with_missing_bundle']->getItemDefinition()->getSetting('handler_settings')['target_bundles']);
+
+    try {
+      $this->resourceTypeRepository->get('node', 'foo')->getRelatableResourceTypesByField('field_ref_with_missing_bundle');
+      static::fail('The above code must produce a warning since the "missing_bundle" does not exist.');
+    }
+    catch (Warning $e) {
+      static::assertSame(
+        'The "field_ref_with_missing_bundle" at "node:foo" references the "node:missing_bundle" entity type that does not exist. Please take action.',
+        $e->getMessage()
+      );
+    }
+  }
+
 }
diff --git a/core/modules/jsonapi/tests/src/Kernel/ResourceType/ResourceTypeNameAliasTest.php b/core/modules/jsonapi/tests/src/Kernel/ResourceType/ResourceTypeNameAliasTest.php
new file mode 100644
index 0000000000..5ba541a729
--- /dev/null
+++ b/core/modules/jsonapi/tests/src/Kernel/ResourceType/ResourceTypeNameAliasTest.php
@@ -0,0 +1,87 @@
+<?php
+
+namespace Drupal\Tests\jsonapi\Kernel\ResourceType;
+
+use Drupal\jsonapi\ResourceType\ResourceType;
+use Drupal\Tests\jsonapi\Kernel\JsonapiKernelTestBase;
+
+/**
+ * Ensures that JSON:API doesn't malfunction on aliased resource type names.
+ *
+ * Despite JSON:API having a limited public PHP API, contrib and custom
+ * modules have found ways to rename resource types (e.g. "user--user" to
+ * "user") which causes JSON:API to malfunction. This results in confusion and
+ * bug reports. Since aliasing resource type names is a feature that JSON:API
+ * will eventually support, this test will help prevent future regressions and
+ * lower the present support burden.
+ *
+ * @coversDefaultClass \Drupal\jsonapi\ResourceType\ResourceTypeRepository
+ * @group jsonapi
+ *
+ * @internal
+ *
+ * @link https://www.drupal.org/project/drupal/issues/2996114
+ *
+ * @todo move this test coverage to ResourceTypeRepositoryTest::testResourceTypeNameAliasing in https://www.drupal.org/project/drupal/issues/3105318
+ */
+class ResourceTypeNameAliasTest extends JsonapiKernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = [
+    'node',
+    'user',
+    'field',
+    'system',
+    'serialization',
+    'jsonapi_test_resource_type_aliasing',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+
+    $this->container
+      ->get('entity_type.manager')
+      ->getStorage('node_type')
+      ->create(['type' => 'page'])
+      ->save();
+  }
+
+  /**
+   * Ensures resource repository works with publicly renamed resource types.
+   *
+   * @covers ::get
+   * @covers ::all
+   * @covers ::getByTypeName
+   */
+  public function test() {
+    $repository = $this->container->get('jsonapi.resource_type.repository');
+
+    static::assertInstanceOf(ResourceType::class, $repository->get('user', 'user'));
+    static::assertNull($repository->getByTypeName('user--user'));
+    static::assertInstanceOf(ResourceType::class, $repository->getByTypeName('user==user'));
+
+    static::assertInstanceOf(ResourceType::class, $repository->get('node', 'page'));
+    static::assertNull($repository->getByTypeName('node--page'));
+    static::assertInstanceOf(ResourceType::class, $repository->getByTypeName('node==page'));
+
+    foreach ($repository->all() as $id => $resource_type) {
+      static::assertSame(
+        $resource_type->getTypeName(),
+        $id,
+        'The key is always equal to the type name.'
+      );
+
+      static::assertNotSame(
+        sprintf('%s--%s', $resource_type->getEntityTypeId(), $resource_type->getBundle()),
+        $id,
+        'The type name can be renamed so it differs from the internal.'
+      );
+    }
+  }
+
+}
diff --git a/core/modules/jsonapi/tests/src/Kernel/ResourceType/ResourceTypeRepositoryTest.php b/core/modules/jsonapi/tests/src/Kernel/ResourceType/ResourceTypeRepositoryTest.php
index d4461fe9c9..54b6ed07b1 100644
--- a/core/modules/jsonapi/tests/src/Kernel/ResourceType/ResourceTypeRepositoryTest.php
+++ b/core/modules/jsonapi/tests/src/Kernel/ResourceType/ResourceTypeRepositoryTest.php
@@ -187,6 +187,16 @@ public function testResourceTypeFieldAliasing() {
     $this->assertSame($this->resourceTypeRepository->getByTypeName('node--page')->getPublicName('uid'), 'owner');
   }
 
+  /**
+   * Tests that resource type fields can be aliased per resource type.
+   */
+  public function testResourceTypeNameAliasing() {
+    // When this test is implemented, ensure the the tested behaviors in
+    // ResourceTypeNameAliasTest have been covered and remove it. Then remove
+    // the jsonapi_test_resource_type_aliasing test module.
+    $this->markTestSkipped('Unskip this test in https://www.drupal.org/project/drupal/issues/3105318');
+  }
+
   /**
    * Tests that resource type fields can be disabled per resource type.
    */