diff --git a/core/misc/ajax.es6.js b/core/misc/ajax.es6.js
index daa62548a0..a2be21678f 100644
--- a/core/misc/ajax.es6.js
+++ b/core/misc/ajax.es6.js
@@ -953,7 +953,11 @@
       const settings = this.settings || drupalSettings;
       Drupal.attachBehaviors(this.$form.get(0), settings);
     }
-    throw new Drupal.AjaxError(xmlhttprequest, uri, customMessage);
+    // Do not throw an error if an ajax request has been interrupted due to
+    // leaving the page.
+    if (!(xmlhttprequest.status === 0 && Drupal.beforeUnloadCalled)) {
+      throw new Drupal.AjaxError(xmlhttprequest, uri, customMessage);
+    }
   };
 
   /**
diff --git a/core/misc/ajax.js b/core/misc/ajax.js
index 1e15175edd..30dc719c44 100644
--- a/core/misc/ajax.js
+++ b/core/misc/ajax.js
@@ -463,7 +463,10 @@ function _toConsumableArray(arr) { if (Array.isArray(arr)) { for (var i = 0, arr
       var settings = this.settings || drupalSettings;
       Drupal.attachBehaviors(this.$form.get(0), settings);
     }
-    throw new Drupal.AjaxError(xmlhttprequest, uri, customMessage);
+
+    if (!(xmlhttprequest.status === 0 && Drupal.beforeUnloadCalled)) {
+      throw new Drupal.AjaxError(xmlhttprequest, uri, customMessage);
+    }
   };
 
   Drupal.AjaxCommands = function () {};
diff --git a/core/misc/drupal.es6.js b/core/misc/drupal.es6.js
index e64f9dac0d..60916d8e3f 100644
--- a/core/misc/drupal.es6.js
+++ b/core/misc/drupal.es6.js
@@ -43,6 +43,18 @@ window.Drupal = { behaviors: {}, locale: {} };
 // JavaScript should be made compatible with libraries other than jQuery by
 // wrapping it in an anonymous closure.
 (function (Drupal, drupalSettings, drupalTranslations) {
+
+  /**
+   * Add a global variable which determines if the window is being unloaded.
+   */
+  Drupal.beforeUnloadCalled = false;
+  window.addEventListener('beforeunload', function () {
+    Drupal.beforeUnloadCalled = true;
+  });
+  window.addEventListener('pagehide', function () {
+    Drupal.beforeUnloadCalled = true;
+  });
+
   /**
    * Helper to rethrow errors asynchronously.
    *
diff --git a/core/misc/drupal.js b/core/misc/drupal.js
index a00d8ce548..10f571ed10 100644
--- a/core/misc/drupal.js
+++ b/core/misc/drupal.js
@@ -8,6 +8,14 @@
 window.Drupal = { behaviors: {}, locale: {} };
 
 (function (Drupal, drupalSettings, drupalTranslations) {
+  Drupal.beforeUnloadCalled = false;
+  window.addEventListener('beforeunload', function () {
+    Drupal.beforeUnloadCalled = true;
+  });
+  window.addEventListener('pagehide', function () {
+    Drupal.beforeUnloadCalled = true;
+  });
+
   Drupal.throwError = function (error) {
     setTimeout(function () {
       throw error;