diff --git a/core/modules/update/templates/update-version.html.twig b/core/modules/update/templates/update-version.html.twig
index b9fba5eaab..5ca4ce46dd 100644
--- a/core/modules/update/templates/update-version.html.twig
+++ b/core/modules/update/templates/update-version.html.twig
@@ -36,7 +36,10 @@
         </li>
         {% if version.core_compatibility_message %}
           <li class="project-update__compatibility-details">
-            <details open="{{ not version.core_compatible }}">
+            <details {% if not version.core_compatible%}open{% endif %}>
+              <summary>
+                {% if version.core_compatible %}{{ 'Compatible'|t }}{% else %}{{ 'Incompatible'|t }}{% endif %}
+              </summary>
               {{ version.core_compatibility_message }}
             </details>
           </li>
diff --git a/core/modules/update/tests/modules/update_test/aaa_update_test.sec.8.x-1.2_8.x-2.2.xml b/core/modules/update/tests/modules/update_test/aaa_update_test.core_compatibility.8.x-1.2_8.x-2.2.xml
similarity index 96%
copy from core/modules/update/tests/modules/update_test/aaa_update_test.sec.8.x-1.2_8.x-2.2.xml
copy to core/modules/update/tests/modules/update_test/aaa_update_test.core_compatibility.8.x-1.2_8.x-2.2.xml
index 038e55e455..1d4fd3a07a 100644
--- a/core/modules/update/tests/modules/update_test/aaa_update_test.sec.8.x-1.2_8.x-2.2.xml
+++ b/core/modules/update/tests/modules/update_test/aaa_update_test.core_compatibility.8.x-1.2_8.x-2.2.xml
@@ -47,7 +47,7 @@
   <release>
    <name>aaa_update_test 8.x-2.2</name>
    <version>8.x-2.2</version>
-   <tag>DRUPAL-8--2-2</tag>
+   <tag>8.x-2.2</tag>
    <core_compatibility>^8.1.1</core_compatibility>
    <status>published</status>
    <release_link>http://example.com/aaa_update_test-8-x-2-2-release</release_link>
@@ -62,7 +62,7 @@
   <release>
    <name>aaa_update_test 8.x-2.1</name>
    <version>8.x-2.1</version>
-   <tag>DRUPAL-8--2-1</tag>
+   <tag>8.x-2.2</tag>
    <status>published</status>
    <release_link>http://example.com/aaa_update_test-8-x-2-1-release</release_link>
    <download_link>http://example.com/aaa_update_test-8-x-2-1.tar.gz</download_link>
@@ -77,7 +77,7 @@
   <release>
    <name>aaa_update_test 8.x-2.0</name>
    <version>8.x-2.0</version>
-   <tag>DRUPAL-8--2-0</tag>
+   <tag>8.x-2.2</tag>
    <status>published</status>
    <release_link>http://example.com/aaa_update_test-8-x-2-0-release</release_link>
    <download_link>http://example.com/aaa_update_test-8-x-2-0.tar.gz</download_link>
@@ -91,7 +91,7 @@
   <release>
    <name>aaa_update_test 8.x-1.2</name>
    <version>8.x-1.2</version>
-   <tag>DRUPAL-8--1-2</tag>
+   <tag>8.x-2.2</tag>
    <core_compatibility>^8.1.0</core_compatibility>
    <status>published</status>
    <release_link>http://example.com/aaa_update_test-8-x-1-2-release</release_link>
@@ -106,7 +106,7 @@
   <release>
    <name>aaa_update_test 8.x-1.1</name>
    <version>8.x-1.1</version>
-   <tag>DRUPAL-8--1-1</tag>
+   <tag>8.x-2.2</tag>
    <status>published</status>
    <release_link>http://example.com/aaa_update_test-8-x-1-1-release</release_link>
    <download_link>http://example.com/aaa_update_test-8-x-1-1.tar.gz</download_link>
@@ -120,7 +120,7 @@
   <release>
    <name>aaa_update_test 8.x-1.0</name>
    <version>8.x-1.0</version>
-   <tag>DRUPAL-8--1-0</tag>
+   <tag>8.x-2.2</tag>
    <status>published</status>
    <release_link>http://example.com/aaa_update_test-8-x-1-0-release</release_link>
    <download_link>http://example.com/aaa_update_test-8-x-1-0.tar.gz</download_link>
diff --git a/core/modules/update/tests/modules/update_test/aaa_update_test.sec.8.x-1.2_8.x-2.2.xml b/core/modules/update/tests/modules/update_test/aaa_update_test.sec.8.x-1.2_8.x-2.2.xml
index 038e55e455..a820b29ac7 100644
--- a/core/modules/update/tests/modules/update_test/aaa_update_test.sec.8.x-1.2_8.x-2.2.xml
+++ b/core/modules/update/tests/modules/update_test/aaa_update_test.sec.8.x-1.2_8.x-2.2.xml
@@ -30,7 +30,6 @@
    <name>aaa_update_test 8.x-3.0-beta1</name>
    <version>8.x-3.0-beta1</version>
    <tag>8.x-3.0-beta1</tag>
-   <core_compatibility>^8.1.1</core_compatibility>
    <status>published</status>
    <release_link>http://example.com/aaa_update_test-8-x-3-0-beta1</release_link>
    <download_link>http://example.com/aaa_update_test--8-x-3-0-beta1.tar.gz</download_link>
@@ -48,7 +47,6 @@
    <name>aaa_update_test 8.x-2.2</name>
    <version>8.x-2.2</version>
    <tag>DRUPAL-8--2-2</tag>
-   <core_compatibility>^8.1.1</core_compatibility>
    <status>published</status>
    <release_link>http://example.com/aaa_update_test-8-x-2-2-release</release_link>
    <download_link>http://example.com/aaa_update_test-8-x-2-2.tar.gz</download_link>
@@ -92,7 +90,6 @@
    <name>aaa_update_test 8.x-1.2</name>
    <version>8.x-1.2</version>
    <tag>DRUPAL-8--1-2</tag>
-   <core_compatibility>^8.1.0</core_compatibility>
    <status>published</status>
    <release_link>http://example.com/aaa_update_test-8-x-1-2-release</release_link>
    <download_link>http://example.com/aaa_update_test-8-x-1-2.tar.gz</download_link>
diff --git a/core/modules/update/tests/src/Functional/UpdateContribTest.php b/core/modules/update/tests/src/Functional/UpdateContribTest.php
index 5e1a1025d6..7e47fa165f 100644
--- a/core/modules/update/tests/src/Functional/UpdateContribTest.php
+++ b/core/modules/update/tests/src/Functional/UpdateContribTest.php
@@ -578,9 +578,9 @@ public function testCoreCompatibilityMessage() {
 
     // Confirm that messages are displayed for security and 'Also available'
     // updates.
-    $this->refreshUpdateStatus(['drupal' => '1.1', 'aaa_update_test' => 'sec.8.x-1.2_8.x-2.2']);
-    $this->assertCoreCompatibilityMessage('8.x-1.2', '8.1.0 to 8.1.1', 'Security update:');
-    $this->assertCoreCompatibilityMessage('8.x-2.2', '8.1.1', 'Also available:');
+    $this->refreshUpdateStatus(['drupal' => '1.1', 'aaa_update_test' => 'core_compatibility.8.x-1.2_8.x-2.2']);
+    $this->assertCoreCompatibilityMessage('8.x-1.2', '8.1.0 to 8.1.1', 'Security update:', FALSE);
+    $this->assertCoreCompatibilityMessage('8.x-2.2', '8.1.1', 'Also available:', FALSE);
   }
 
   /**
@@ -718,14 +718,34 @@ public function securityUpdateAvailabilityProvider() {
    *   The expected core compatibility range.
    * @param string $expected_release_title
    *   The expected release title.
+   * @param bool $is_compatible
+   *   If the update is compatible with the installed version of Drupal.
    */
-  protected function assertCoreCompatibilityMessage($version, $expected_compatibility_range, $expected_release_title) {
+  protected function assertCoreCompatibilityMessage($version, $expected_compatibility_range, $expected_release_title, $is_compatible = TRUE) {
     $link = $this->getSession()->getPage()->findLink($version);
     $update_info_element = $link->getParent();
-    $update_compatibility_details_element = $update_info_element->getParent()->find('css', '.project-update__compatibility-details');
+    $update_compatibility_details_element = $update_info_element->getParent()->find('css', '.project-update__compatibility-details details');
     $this->assertContains("Requires Drupal core: $expected_compatibility_range", $update_compatibility_details_element->getText());
     $update_title_element = $update_info_element->getParent()->find('css', '.project-update__version-title');
     $this->assertSame($expected_release_title, $update_title_element->getText());
+    $details_summary_element = $update_compatibility_details_element->find('css', 'summary');
+    if ($is_compatible) {
+      $download_version = str_replace('.', '-', $version);
+      // If an update is compatible with the installed version of Drupal
+      // core it should have a download link and the details element
+      // should not be open by default.
+      $this->assertFalse($update_compatibility_details_element->hasAttribute('open'));
+      $this->assertSame('Compatible', $details_summary_element->getText());
+      $this->assertEquals($update_info_element->getParent()->findLink('Download')->getAttribute('href'), "http://example.com/{$this->updateProject}-$download_version.tar.gz");
+    }
+    else {
+      // If an update is not compatible with the installed version of Drupal
+      // core it should not have a download link and the details element
+      // should be open by default.
+      $this->assertTrue($update_compatibility_details_element->hasAttribute('open'));
+      $this->assertSame('Incompatible', $details_summary_element->getText());
+      $this->assertFalse($update_info_element->getParent()->hasLink('Download'));
+    }
   }
 
 }
diff --git a/core/themes/claro/templates/admin/update-version.html.twig b/core/themes/claro/templates/admin/update-version.html.twig
index 250c7b110d..250305e310 100644
--- a/core/themes/claro/templates/admin/update-version.html.twig
+++ b/core/themes/claro/templates/admin/update-version.html.twig
@@ -34,7 +34,10 @@
         </li>
         {% if version.core_compatibility_message %}
           <li class="project-update__compatibility-details">
-            <details open="{{ not version.core_compatible }}">
+            <details {% if not version.core_compatible%}open{% endif %}>
+              <summary>
+                {% if version.core_compatible %}{{ 'Compatible'|t }}{% else %}{{ 'Incompatible'|t }}{% endif %}
+              </summary>
               {{ version.core_compatibility_message }}
             </details>
           </li>
diff --git a/core/themes/stable/templates/admin/update-version.html.twig b/core/themes/stable/templates/admin/update-version.html.twig
index 38c386e1cc..f9f1ff8811 100644
--- a/core/themes/stable/templates/admin/update-version.html.twig
+++ b/core/themes/stable/templates/admin/update-version.html.twig
@@ -34,7 +34,10 @@
         </li>
         {% if version.core_compatibility_message %}
           <li class="project-update__compatibility-details">
-            <details open="{{ not version.core_compatible }}">
+            <details {% if not version.core_compatible%}open{% endif %}>
+              <summary>
+                {% if version.core_compatible %}{{ 'Compatible'|t }}{% else %}{{ 'Incompatible'|t }}{% endif %}
+              </summary>
               {{ version.core_compatibility_message }}
             </details>
           </li>