core/modules/aggregator/src/Entity/Feed.php        |  1 +
 .../block_content/src/Entity/BlockContent.php      |  1 +
 core/modules/comment/src/Entity/Comment.php        |  1 +
 core/modules/node/src/Entity/Node.php              |  1 +
 core/modules/rest/rest.services.yml                |  8 ++++
 .../PathProcessorEntityResourceBC.php              | 51 ++++++++++++++++++++++
 .../rest/src/Plugin/Deriver/EntityDeriver.php      |  2 +-
 core/modules/rest/src/Plugin/ResourceBase.php      |  7 ++-
 .../modules/entity_test/src/Entity/EntityTest.php  |  1 +
 .../src/Entity/EntityTestWithBundle.php            |  1 +
 .../src/Entity/EntityTestWithRevisionLog.php       |  1 +
 core/modules/taxonomy/src/Entity/Term.php          |  1 +
 core/modules/user/src/Entity/User.php              |  1 +
 13 files changed, 74 insertions(+), 3 deletions(-)

diff --git a/core/modules/aggregator/src/Entity/Feed.php b/core/modules/aggregator/src/Entity/Feed.php
index 834a55e..8aae7ca 100644
--- a/core/modules/aggregator/src/Entity/Feed.php
+++ b/core/modules/aggregator/src/Entity/Feed.php
@@ -33,6 +33,7 @@
  *     "canonical" = "/aggregator/sources/{aggregator_feed}",
  *     "edit-form" = "/aggregator/sources/{aggregator_feed}/configure",
  *     "delete-form" = "/aggregator/sources/{aggregator_feed}/delete",
+ *     "create" = "/aggregator/sources",
  *   },
  *   field_ui_base_route = "aggregator.admin_overview",
  *   base_table = "aggregator_feed",
diff --git a/core/modules/block_content/src/Entity/BlockContent.php b/core/modules/block_content/src/Entity/BlockContent.php
index 51ae6f6..f87ab1d 100644
--- a/core/modules/block_content/src/Entity/BlockContent.php
+++ b/core/modules/block_content/src/Entity/BlockContent.php
@@ -41,6 +41,7 @@
  *     "delete-form" = "/block/{block_content}/delete",
  *     "edit-form" = "/block/{block_content}",
  *     "collection" = "/admin/structure/block/block-content",
+ *     "create" = "/block",
  *   },
  *   translatable = TRUE,
  *   entity_keys = {
diff --git a/core/modules/comment/src/Entity/Comment.php b/core/modules/comment/src/Entity/Comment.php
index d52f04d..a63a8b3 100644
--- a/core/modules/comment/src/Entity/Comment.php
+++ b/core/modules/comment/src/Entity/Comment.php
@@ -57,6 +57,7 @@
  *     "canonical" = "/comment/{comment}",
  *     "delete-form" = "/comment/{comment}/delete",
  *     "edit-form" = "/comment/{comment}/edit",
+ *     "create" = "/comment",
  *   },
  *   bundle_entity_type = "comment_type",
  *   field_ui_base_route  = "entity.comment_type.edit_form",
diff --git a/core/modules/node/src/Entity/Node.php b/core/modules/node/src/Entity/Node.php
index bb0e36a..5a99d96 100644
--- a/core/modules/node/src/Entity/Node.php
+++ b/core/modules/node/src/Entity/Node.php
@@ -71,6 +71,7 @@
  *     "edit-form" = "/node/{node}/edit",
  *     "version-history" = "/node/{node}/revisions",
  *     "revision" = "/node/{node}/revisions/{node_revision}/view",
+ *     "create" = "/node",
  *   }
  * )
  */
diff --git a/core/modules/rest/rest.services.yml b/core/modules/rest/rest.services.yml
index 2def91e..a1adc3a 100644
--- a/core/modules/rest/rest.services.yml
+++ b/core/modules/rest/rest.services.yml
@@ -40,3 +40,11 @@ services:
     tags:
       - { name: event_subscriber }
     arguments: ['@serializer', '@renderer', '@current_route_match']
+
+  # @todo Remove in Drupal 9.0.0.
+  rest.path_processor_entity_resource_bc:
+    class: \Drupal\rest\PathProcessor\PathProcessorEntityResourceBC
+    arguments: ['@entity_type.manager']
+    tags:
+      - { name: path_processor_inbound }
+
diff --git a/core/modules/rest/src/PathProcessor/PathProcessorEntityResourceBC.php b/core/modules/rest/src/PathProcessor/PathProcessorEntityResourceBC.php
new file mode 100644
index 0000000..6128278
--- /dev/null
+++ b/core/modules/rest/src/PathProcessor/PathProcessorEntityResourceBC.php
@@ -0,0 +1,51 @@
+<?php
+
+namespace Drupal\rest\PathProcessor;
+
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Drupal\Core\PathProcessor\InboundPathProcessorInterface;
+use Symfony\Component\HttpFoundation\Request;
+
+/**
+ * Path processor to maintain BC for entity REST resource URLs from Drupal 8.0.
+ */
+class PathProcessorEntityResourceBC implements InboundPathProcessorInterface {
+
+  /**
+   * The entity type manager.
+   *
+   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
+   */
+  protected $entityTypeManager;
+
+  /**
+   * Creates a new PathProcessorEntityResourceBC instance.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
+   *   The entity type manager.
+   */
+  public function __construct(EntityTypeManagerInterface $entity_type_manager) {
+    $this->entityTypeManager = $entity_type_manager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function processInbound($path, Request $request) {
+    if ($request->getMethod() === 'POST' && strpos($path, '/entity/') === 0) {
+      $parts = explode('/', $path);
+      $entity_type = array_pop($parts);
+
+      // Only remove the '/entity' prefix if we have a matching entity type
+      // following it. Otherwise, this is a route other than the one for
+      // \Drupal\rest\Plugin\rest\resource\EntityResource, and hence we don't
+      // want to change anything.
+      if ($this->entityTypeManager->getDefinition($entity_type)->hasLinkTemplate('https://www.drupal.org/link-relations/create')) {
+        // Return the path minus the leading '/entity'.
+        return substr($path, 7);
+      }
+    }
+    return $path;
+  }
+
+}
diff --git a/core/modules/rest/src/Plugin/Deriver/EntityDeriver.php b/core/modules/rest/src/Plugin/Deriver/EntityDeriver.php
index 6a6ddae..b98811c 100644
--- a/core/modules/rest/src/Plugin/Deriver/EntityDeriver.php
+++ b/core/modules/rest/src/Plugin/Deriver/EntityDeriver.php
@@ -74,7 +74,7 @@ public function getDerivativeDefinitions($base_plugin_definition) {
 
         $default_uris = array(
           'canonical' => "/entity/$entity_type_id/" . '{' . $entity_type_id . '}',
-          'https://www.drupal.org/link-relations/create' => "/entity/$entity_type_id",
+          'create' => "/entity/$entity_type_id",
         );
 
         foreach ($default_uris as $link_relation => $default_uri) {
diff --git a/core/modules/rest/src/Plugin/ResourceBase.php b/core/modules/rest/src/Plugin/ResourceBase.php
index 93684db..63498db 100644
--- a/core/modules/rest/src/Plugin/ResourceBase.php
+++ b/core/modules/rest/src/Plugin/ResourceBase.php
@@ -100,8 +100,11 @@ public function routes() {
 
     $definition = $this->getPluginDefinition();
     $canonical_path = isset($definition['uri_paths']['canonical']) ? $definition['uri_paths']['canonical'] : '/' . strtr($this->pluginId, ':', '/') . '/{id}';
-    $create_path = isset($definition['uri_paths']['https://www.drupal.org/link-relations/create']) ? $definition['uri_paths']['https://www.drupal.org/link-relations/create'] : '/' . strtr($this->pluginId, ':', '/');
-
+    $create_path = isset($definition['uri_paths']['create']) ? $definition['uri_paths']['create'] : '/' . strtr($this->pluginId, ':', '/');
+    // BC.
+    if (!isset($definition['uri_paths']['create']) && isset($definition['uri_paths']['https://www.drupal.org/link-relations/create'])) {
+      $create_path = $definition['uri_paths']['https://www.drupal.org/link-relations/create'];
+    }
     $route_name = strtr($this->pluginId, ':', '.');
 
     $methods = $this->availableMethods();
diff --git a/core/modules/system/tests/modules/entity_test/src/Entity/EntityTest.php b/core/modules/system/tests/modules/entity_test/src/Entity/EntityTest.php
index a603f53..f169bd7 100644
--- a/core/modules/system/tests/modules/entity_test/src/Entity/EntityTest.php
+++ b/core/modules/system/tests/modules/entity_test/src/Entity/EntityTest.php
@@ -45,6 +45,7 @@
  *     "add-form" = "/entity_test/add",
  *     "edit-form" = "/entity_test/manage/{entity_test}/edit",
  *     "delete-form" = "/entity_test/delete/entity_test/{entity_test}",
+ *     "create" = "/entity_test",
  *   },
  *   field_ui_base_route = "entity.entity_test.admin_form",
  * )
diff --git a/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestWithBundle.php b/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestWithBundle.php
index c668bd3..e6cb542 100644
--- a/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestWithBundle.php
+++ b/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestWithBundle.php
@@ -41,6 +41,7 @@
  *     "add-form" = "/entity_test_with_bundle/add/{entity_test_bundle}",
  *     "edit-form" = "/entity_test_with_bundle/{entity_test_with_bundle}/edit",
  *     "delete-form" = "/entity_test_with_bundle/{entity_test_with_bundle}/delete",
+ *     "create" = "/entity_test_with_bundle",
  *   },
  * )
  */
diff --git a/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestWithRevisionLog.php b/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestWithRevisionLog.php
index 4f4f4f1..33054fb 100644
--- a/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestWithRevisionLog.php
+++ b/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestWithRevisionLog.php
@@ -40,6 +40,7 @@
  *     "delete-form" = "/entity_test/delete/entity_test_revlog/{entity_test_revlog}",
  *     "edit-form" = "/entity_test_revlog/manage/{entity_test_revlog}/edit",
  *     "revision" = "/entity_test_revlog/{entity_test_revlog}/revision/{entity_test_revlog_revision}/view",
+ *     "create" = "/entity_test_revlog",
  *   }
  * )
  */
diff --git a/core/modules/taxonomy/src/Entity/Term.php b/core/modules/taxonomy/src/Entity/Term.php
index 5b0072b..206829f 100644
--- a/core/modules/taxonomy/src/Entity/Term.php
+++ b/core/modules/taxonomy/src/Entity/Term.php
@@ -46,6 +46,7 @@
  *     "canonical" = "/taxonomy/term/{taxonomy_term}",
  *     "delete-form" = "/taxonomy/term/{taxonomy_term}/delete",
  *     "edit-form" = "/taxonomy/term/{taxonomy_term}/edit",
+ *     "create" = "/taxonomy_term",
  *   },
  *   permission_granularity = "bundle"
  * )
diff --git a/core/modules/user/src/Entity/User.php b/core/modules/user/src/Entity/User.php
index 062af44..3be0e79 100644
--- a/core/modules/user/src/Entity/User.php
+++ b/core/modules/user/src/Entity/User.php
@@ -51,6 +51,7 @@
  *     "edit-form" = "/user/{user}/edit",
  *     "cancel-form" = "/user/{user}/cancel",
  *     "collection" = "/admin/people",
+ *     "create" = "/user",
  *   },
  *   field_ui_base_route = "entity.user.admin_form",
  *   common_reference_target = TRUE