diff --git a/core/misc/ajax.es6.js b/core/misc/ajax.es6.js
index c3633b4636..5c21be0f10 100644
--- a/core/misc/ajax.es6.js
+++ b/core/misc/ajax.es6.js
@@ -479,12 +479,20 @@
         return ajax.beforeSerialize(elementSettings, options);
       },
       beforeSubmit(formValues, elementSettings, options) {
+        const continueSubmit = ajax.beforeSubmit(formValues, elementSettings, options);
+        if (continueSubmit === false) {
+          return false;
+        }
         ajax.ajaxing = true;
-        return ajax.beforeSubmit(formValues, elementSettings, options);
+        return continueSubmit;
       },
       beforeSend(xmlhttprequest, options) {
+        const continueSend = ajax.beforeSend(xmlhttprequest, options);
+        if (continueSend === false) {
+          return false;
+        }
         ajax.ajaxing = true;
-        return ajax.beforeSend(xmlhttprequest, options);
+        return continueSend;
       },
       success(response, status, xmlhttprequest) {
         // Sanity check for browser support (object expected).
diff --git a/core/misc/ajax.js b/core/misc/ajax.js
index 58759ac7a0..f6420f3c5a 100644
--- a/core/misc/ajax.js
+++ b/core/misc/ajax.js
@@ -204,12 +204,20 @@ function _toConsumableArray(arr) { if (Array.isArray(arr)) { for (var i = 0, arr
         return ajax.beforeSerialize(elementSettings, options);
       },
       beforeSubmit: function beforeSubmit(formValues, elementSettings, options) {
+        var continueSubmit = ajax.beforeSubmit(formValues, elementSettings, options);
+        if (continueSubmit === false) {
+          return false;
+        }
         ajax.ajaxing = true;
-        return ajax.beforeSubmit(formValues, elementSettings, options);
+        return continueSubmit;
       },
       beforeSend: function beforeSend(xmlhttprequest, options) {
+        var continueSend = ajax.beforeSend(xmlhttprequest, options);
+        if (continueSend === false) {
+          return false;
+        }
         ajax.ajaxing = true;
-        return ajax.beforeSend(xmlhttprequest, options);
+        return continueSend;
       },
       success: function success(response, status, xmlhttprequest) {
         if (typeof response === 'string') {