diff -u b/core/modules/field/tests/src/FunctionalJavascript/FormJSAddMoreTest.php b/core/modules/field/tests/src/FunctionalJavascript/FormJSAddMoreTest.php
--- b/core/modules/field/tests/src/FunctionalJavascript/FormJSAddMoreTest.php
+++ b/core/modules/field/tests/src/FunctionalJavascript/FormJSAddMoreTest.php
@@ -68,10 +68,7 @@
 
     // Add another item.
     $add_more_button->click();
-    $assert_session->assertWaitOnAjaxRequest();
-
-    // Validate the existence of the new field.
-    $field_1 = $page->findField('field_unlimited[1][value]');
+    $field_1 = $assert_session->waitForField('field_unlimited[1][value]');
     $this->assertNotEmpty($field_1, 'Successfully added another item.');
 
     // Validate the value of the first field has not changed.
@@ -82,10 +79,7 @@
 
     // Add another item.
     $add_more_button->click();
-    $assert_session->assertWaitOnAjaxRequest();
-
-    // Assert successful creation.
-    $field_2 = $page->findField('field_unlimited[2][value]');
+    $field_2 = $assert_session->waitForField('field_unlimited[2][value]');
     $this->assertNotEmpty($field_2, 'Successfully added another item.');
 
     // Set values for the 2nd and 3rd fields to validate dragging.