diff -u b/core/modules/image/tests/src/FunctionalJavascript/QuickEditImageTest.php b/core/modules/image/tests/src/FunctionalJavascript/QuickEditImageTest.php
--- b/core/modules/image/tests/src/FunctionalJavascript/QuickEditImageTest.php
+++ b/core/modules/image/tests/src/FunctionalJavascript/QuickEditImageTest.php
@@ -148,9 +148,12 @@
       . 'jQuery(".quickedit-image-dropzone").trigger(e);';
     $this->getSession()->executeScript($script);
 
+    // Wait for AJAX to finish.
+    $this->assertSession()->assertWaitOnAjaxRequest();
+
     // Wait for the dropzone element to be removed (i.e. loading is done).
     $condition = "jQuery('" . $field_selector . " .quickedit-image-dropzone').length == 0";
-    $this->assertJsCondition($condition, 20000);
+    $this->assertJsCondition($condition, 10000);
 
     // To prevent 403s on save, we re-set our request (cookie) state.
     $this->prepareRequest();