diff --git a/core/tests/Drupal/FunctionalTests/AssertLegacyTrait.php b/core/tests/Drupal/FunctionalTests/AssertLegacyTrait.php
index a1afabe..5b18f38 100644
--- a/core/tests/Drupal/FunctionalTests/AssertLegacyTrait.php
+++ b/core/tests/Drupal/FunctionalTests/AssertLegacyTrait.php
@@ -688,9 +688,11 @@ protected function assertCacheTag($expected_cache_tag) {
    *
    * @deprecated Scheduled for removal in Drupal 9.0.0.
    *   Use $this->assertSession()->responseHeaderContains() instead.
+   *
+   * @see https://www.drupal.org/node/2864029
    */
   protected function assertCacheContext($expected_cache_context) {
-    @trigger_error('assertCacheContext() is deprecated and scheduled for removal in Drupal 9.0.0. Use $this->assertSession()->responseHeaderContains() instead.', E_USER_DEPRECATED);
+    @trigger_error('assertCacheContext() is deprecated and scheduled for removal in Drupal 9.0.0. Use $this->assertSession()->responseHeaderContains() instead. See https://www.drupal.org/node/2864029.', E_USER_DEPRECATED);
     $this->assertSession()->responseHeaderContains('X-Drupal-Cache-Contexts', $expected_cache_context);
   }
 
@@ -702,9 +704,11 @@ protected function assertCacheContext($expected_cache_context) {
    *
    * @deprecated Scheduled for removal in Drupal 9.0.0.
    *   Use $this->assertSession()->responseHeaderNotContains() instead.
+   *
+   * @see https://www.drupal.org/node/2864029
    */
   protected function assertNoCacheContext($not_expected_cache_context) {
-    @trigger_error('assertNoCacheContext() is deprecated and scheduled for removal in Drupal 9.0.0. Use $this->assertSession()->responseHeaderNotContains() instead.', E_USER_DEPRECATED);
+    @trigger_error('assertNoCacheContext() is deprecated and scheduled for removal in Drupal 9.0.0. Use $this->assertSession()->responseHeaderNotContains() instead. See https://www.drupal.org/node/2864029.', E_USER_DEPRECATED);
     $this->assertSession()->responseHeaderNotContains('X-Drupal-Cache-Contexts', $not_expected_cache_context);
   }