diff --git a/cvat-ui/package-lock.json b/cvat-ui/package-lock.json
index 45c2f0f4..54519190 100644
--- a/cvat-ui/package-lock.json
+++ b/cvat-ui/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "cvat-ui",
-  "version": "1.11.5",
+  "version": "1.11.6",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/cvat-ui/package.json b/cvat-ui/package.json
index b3f718c5..71d8290a 100644
--- a/cvat-ui/package.json
+++ b/cvat-ui/package.json
@@ -1,6 +1,6 @@
 {
   "name": "cvat-ui",
-  "version": "1.11.5",
+  "version": "1.11.6",
   "description": "CVAT single-page application",
   "main": "src/index.tsx",
   "scripts": {
diff --git a/cvat-ui/src/components/annotation-page/standard-workspace/objects-side-bar/object-item-menu.tsx b/cvat-ui/src/components/annotation-page/standard-workspace/objects-side-bar/object-item-menu.tsx
index 9f88ae43..77efbdf3 100644
--- a/cvat-ui/src/components/annotation-page/standard-workspace/objects-side-bar/object-item-menu.tsx
+++ b/cvat-ui/src/components/annotation-page/standard-workspace/objects-side-bar/object-item-menu.tsx
@@ -200,6 +200,7 @@ function RemoveItem(props: ItemProps): JSX.Element {
                     onClick={(): void => {
                         if (locked) {
                             Modal.confirm({
+								className: 'cvat-modal-confirm',
                                 title: 'Object is locked',
                                 content: 'Are you sure you want to remove it?',
                                 onOk() {
diff --git a/cvat-ui/src/components/cvat-app.tsx b/cvat-ui/src/components/cvat-app.tsx
index b3c742cd..7e361bdf 100644
--- a/cvat-ui/src/components/cvat-app.tsx
+++ b/cvat-ui/src/components/cvat-app.tsx
@@ -187,9 +187,11 @@ class CVATApplication extends React.PureComponent<CVATAppProps & RouteComponentP
     }
 
     private showErrors(): void {
-        function showError(title: string, _error: any): void {
+        function showError(title: string, _error: any, className?: string): void {
             const error = _error.toString();
+            const dynamicProps = typeof className === 'undefined' ? {} : { className };
             notification.error({
+                ...dynamicProps,
                 message: (
                     <div
                         // eslint-disable-next-line
@@ -214,7 +216,7 @@ class CVATApplication extends React.PureComponent<CVATAppProps & RouteComponentP
                 const error = (notifications as any).errors[where][what];
                 shown = shown || !!error;
                 if (error) {
-                    showError(error.message, error.reason);
+                    showError(error.message, error.reason, error.className);
                 }
             }
         }
diff --git a/cvat-ui/src/reducers/interfaces.ts b/cvat-ui/src/reducers/interfaces.ts
index 088be88d..e1b215f9 100644
--- a/cvat-ui/src/reducers/interfaces.ts
+++ b/cvat-ui/src/reducers/interfaces.ts
@@ -213,6 +213,7 @@ export interface ModelsState {
 export interface ErrorState {
     message: string;
     reason: string;
+    className?: string;
 }
 
 export interface NotificationsState {
diff --git a/cvat-ui/src/reducers/notifications-reducer.ts b/cvat-ui/src/reducers/notifications-reducer.ts
index 9f2caec0..d1e2b602 100644
--- a/cvat-ui/src/reducers/notifications-reducer.ts
+++ b/cvat-ui/src/reducers/notifications-reducer.ts
@@ -776,6 +776,7 @@ export default function (state = defaultState, action: AnyAction): Notifications
                         removing: {
                             message: 'Could not remove the object',
                             reason: action.payload.error.toString(),
+                            className: 'cvat-notification-notice-remove-object-failed',
                         },
                     },
                 },
diff --git a/tests/cypress/integration/actions_tasks_objects/case_24_delete_unlock_lock_object.js b/tests/cypress/integration/actions_tasks_objects/case_24_delete_unlock_lock_object.js
new file mode 100644
index 00000000..6b8d148d
--- /dev/null
+++ b/tests/cypress/integration/actions_tasks_objects/case_24_delete_unlock_lock_object.js
@@ -0,0 +1,128 @@
+// Copyright (C) 2020 Intel Corporation
+//
+// SPDX-License-Identifier: MIT
+
+/// <reference types="cypress" />
+
+import { taskName, labelName } from '../../support/const';
+
+context('Delete unlock/lock object', () => {
+    const caseId = '24';
+
+    const createRectangleShape2Points = {
+        points: 'By 2 Points',
+        type: 'Shape',
+        labelName: labelName,
+        firstX: 100,
+        firstY: 100,
+        secondX: 300,
+        secondY: 300,
+    };
+
+    function lockObject() {
+        cy.get('.cvat-objects-sidebar-state-item').within(() => {
+            cy.get('.cvat-object-item-button-lock').click();
+        });
+    };
+
+    function deleteObjectViaShortcut(shortcut, stateLockObject) {
+        if (stateLockObject == 'unlock') {
+            cy.get('.cvat-canvas-container').within(() => {
+                cy.get('.cvat_canvas_shape')
+                    .trigger('mousemove')
+                    .should('have.class', 'cvat_canvas_shape_activated');
+            });
+        };
+        cy.get('body')
+            .type(shortcut);
+    };
+
+    function clickRemoveOnDropdownMenu() {
+        cy.get('.cvat-object-item-menu')
+            .contains(new RegExp('^Remove$', 'g'))
+            .click({ force: true });
+    };
+
+    function deleteObjectViaGUIFromSidebar() {
+        cy.get('.cvat-objects-sidebar-states-list').within(() => {
+            cy.get('.cvat-objects-sidebar-state-item').within(() => {
+                cy.get('[aria-label="icon: more"]').click();
+            });
+        });
+        clickRemoveOnDropdownMenu();
+    };
+
+    function deleteObjectViaGUIFromObject() {
+        cy.get('.cvat-canvas-container').within(() => {
+            cy.get('.cvat_canvas_shape')
+                .trigger('mousemove')
+                .rightclick();
+        });
+        cy.get('.cvat-canvas-context-menu').within(() => {
+            cy.get('.cvat-objects-sidebar-state-item').within(() => {
+                cy.get('[aria-label="icon: more"]').click();
+            });
+        });
+        clickRemoveOnDropdownMenu();
+    };
+
+    function actionOnConfirmWindow(textBuntton) {
+        cy.get('.cvat-modal-confirm').within(() => {
+            cy.contains(new RegExp(`^${textBuntton}$`, 'g'))
+                .click();
+        });
+    };
+
+    function checkFailDeleteLockObject(shortcut) {
+        deleteObjectViaShortcut(shortcut, 'lock');
+        checkExistObject('exist');
+        cy.get('.cvat-notification-notice-remove-object-failed').should('exist');
+    };
+
+    function checkExistObject(state) {
+        cy.get('.cvat_canvas_shape').should(state);
+        cy.get('.cvat-objects-sidebar-state-item').should(state);
+    };
+
+    before(() => {
+        cy.openTaskJob(taskName);
+    });
+
+    describe(`Testing case "${caseId}"`, () => {
+        it('Create and delete object via "Delete" shortcut', () => {
+            cy.createRectangle(createRectangleShape2Points);
+            deleteObjectViaShortcut('{del}', 'unlock');
+            checkExistObject('not.exist');
+        });
+
+        it('Create and delete object via GUI from sidebar', () => {
+            cy.createRectangle(createRectangleShape2Points);
+            deleteObjectViaGUIFromSidebar();
+            checkExistObject('not.exist');
+        });
+
+        it('Create, lock and delete object via "Shift+Delete" shortcuts', () => {
+            cy.createRectangle(createRectangleShape2Points);
+            lockObject();
+            checkFailDeleteLockObject('{del}');
+            deleteObjectViaShortcut('{shift}{del}', 'lock');
+            checkExistObject('not.exist');
+        });
+
+        it('Create, lock and delete object via GUI from sidebar', () => {
+            cy.createRectangle(createRectangleShape2Points);
+            lockObject();
+            deleteObjectViaGUIFromSidebar();
+            actionOnConfirmWindow('OK');
+            checkExistObject('not.exist');
+        });
+
+        it('Create, lock and cancel delete object via GUI from object', () => {
+            cy.createRectangle(createRectangleShape2Points);
+            lockObject();
+            deleteObjectViaGUIFromObject();
+            actionOnConfirmWindow('Cancel');
+            checkExistObject('exist');
+        });
+    });
+});