.../src/Functional/EntityResource/EntityResourceTestBase.php     | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
index c72f065..e66442a 100644
--- a/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
+++ b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
@@ -422,9 +422,14 @@ public function testGet() {
     $this->deprovisionEntityResource();
 
 
-    // DX: upon deprovisioning, immediate 404, or 403 if canonical route.
+    // DX: upon deprovisioning, immediate 404 if no route, 406 otherwise.
     $response = $this->request('GET', $url, $request_options);
-    $this->assertSame($has_canonical_url ? 403 : 404, $response->getStatusCode());
+    if (!$has_canonical_url) {
+      $this->assertSame(404, $response->getStatusCode());
+    }
+    else {
+      $this->assert406Response($response);
+    }
 
 
     $this->provisionEntityResource();