diff --git a/framework/CHANGELOG.md b/framework/CHANGELOG.md
index 2ec245ea228..64e997ee82e 100644
--- a/framework/CHANGELOG.md
+++ b/framework/CHANGELOG.md
@@ -4,6 +4,7 @@ Yii Framework 2 Change Log
 2.0.50 under development
 ------------------------
 
+- Bug #13920: Fixed erroneous validation for specific cases (tim-fischer-maschinensucher)
 - Bug #19927: Fixed `console\controllers\MessageController` when saving translations to database: fixed FK error when adding new string and language at the same time, checking/regenerating all missing messages and dropping messages for unused languages (atrandafir)
 - Enh #12743: Added new methods `BaseActiveRecord::loadRelations()` and `BaseActiveRecord::loadRelationsFor()` to eager load related models for existing primary model instances (PowerGamer1)
 
diff --git a/framework/assets/yii.activeForm.js b/framework/assets/yii.activeForm.js
index b12f812c37d..5b9ce4aaec2 100644
--- a/framework/assets/yii.activeForm.js
+++ b/framework/assets/yii.activeForm.js
@@ -395,9 +395,11 @@
                         data: $form.serialize() + extData,
                         dataType: data.settings.ajaxDataType,
                         complete: function (jqXHR, textStatus) {
+                            currentAjaxRequest = null;
                             $form.trigger(events.ajaxComplete, [jqXHR, textStatus]);
                         },
                         beforeSend: function (jqXHR, settings) {
+                            currentAjaxRequest = jqXHR;
                             $form.trigger(events.ajaxBeforeSend, [jqXHR, settings]);
                         },
                         success: function (msgs) {
@@ -563,6 +565,9 @@
             return;
         }
 
+        if (currentAjaxRequest !== null) {
+            currentAjaxRequest.abort();
+        }
         if (data.settings.timer !== undefined) {
             clearTimeout(data.settings.timer);
         }
@@ -929,4 +934,7 @@
             $form.find(attribute.input).attr('aria-invalid', hasError ? 'true' : 'false');
         }
     }
+
+    var currentAjaxRequest = null;
+
 })(window.jQuery);
diff --git a/tests/js/data/yii.activeForm.html b/tests/js/data/yii.activeForm.html
index d44c9f1282b..d278be5b8b8 100644
--- a/tests/js/data/yii.activeForm.html
+++ b/tests/js/data/yii.activeForm.html
@@ -48,3 +48,15 @@
         <div class="help-block"></div>
     </div>
 </form>
+<form id="w3">
+    <div class="form-group field-test-text2 required">
+        <label class="control-label" for="test-text2">Test text</label>
+        <input type="text" id="test-text2" class="form-control" name="Test[text2]" aria-required="true">
+        <div class="help-block"></div>
+    </div>
+    <div class="form-group field-test-text3 required">
+        <label class="control-label" for="test-text3">Test text</label>
+        <input type="text" id="test-text3" class="form-control" name="Test[text3]" aria-required="true">
+        <div class="help-block"></div>
+    </div>
+</form>
diff --git a/tests/js/tests/yii.activeForm.test.js b/tests/js/tests/yii.activeForm.test.js
index 16671239ea3..f79599b0747 100644
--- a/tests/js/tests/yii.activeForm.test.js
+++ b/tests/js/tests/yii.activeForm.test.js
@@ -27,6 +27,21 @@ describe('yii.activeForm', function () {
         var script = new vm.Script(code);
         var context = new vm.createContext({window: window, document: window.document, yii: yii});
         script.runInContext(context);
+        /** This is a workaround for a jsdom issue, that prevents :hidden and :visible from working as expected.
+         * @see https://github.com/jsdom/jsdom/issues/1048 */
+        context.window.Element.prototype.getClientRects = function () {
+            var node = this;
+            while(node) {
+                if(node === document) {
+                    break;
+                }
+                if (!node.style || node.style.display === 'none' || node.style.visibility === 'hidden') {
+                    return [];
+                }
+                node = node.parentNode;
+            }
+            return [{width: 100, height: 100}];
+        };
     }
 
     var activeFormHtml = fs.readFileSync('tests/js/data/yii.activeForm.html', 'utf-8');
@@ -117,6 +132,60 @@ describe('yii.activeForm', function () {
                 assert.isFalse($activeForm.data('yiiActiveForm').validated);
             });
         });
+
+        describe('with ajax validation', function () {
+            describe('with rapid validation of multiple fields', function () {
+                it('should cancel overlapping ajax requests and not display outdated validation results', function () {
+                    $activeForm = $('#w3');
+                    $activeForm.yiiActiveForm([{
+                        id: 'test-text2',
+                        input: '#test-text2',
+                        container: '.field-test-text2',
+                        enableAjaxValidation: true
+                    }, {
+                        id: 'test-text3',
+                        input: '#test-text3',
+                        container: '.field-test-text3',
+                        enableAjaxValidation: true
+                    }], {
+                        validationUrl: ''
+                    });
+
+                    let requests = [];
+                    function fakeAjax(object) {
+                        const request = {
+                            jqXHR: {
+                                abort: function () {
+                                    request.aborted = true;
+                                }
+                            },
+                            aborted: false,
+                            respond: function (response) {
+                                if (this.aborted) {
+                                    return;
+                                }
+                                object.success(response);
+                                object.complete(this.jqXHR, '');
+                            }
+                        };
+                        requests.push(request);
+                        object.beforeSend(request.jqXHR, '');
+                    }
+
+                    const ajaxStub = sinon.stub($, 'ajax', fakeAjax);
+                    $activeForm.yiiActiveForm('validateAttribute', 'test-text2');
+                    assert.isTrue(requests.length === 1);
+                    $activeForm.yiiActiveForm('validateAttribute', 'test-text3');
+                    // When validateAttribute was called on text2, its value was valid.
+                    // The value of text3 wasn't.
+                    requests[0].respond({'test-text3': ['Field cannot be empty']});
+                    // When validateAttribute was called on text3, its value was valid.
+                    requests[1].respond([]);
+                    assert.isTrue($activeForm.find('.field-test-text3').hasClass('has-success'));
+                    ajaxStub.restore();
+                });
+            });
+        })
     });
 
     describe('resetForm method', function () {