diff --git a/src/containers/ReviewActions/components/StartGradingButton.jsx b/src/containers/ReviewActions/components/StartGradingButton.jsx
index ce40ea4..db80cbe 100644
--- a/src/containers/ReviewActions/components/StartGradingButton.jsx
+++ b/src/containers/ReviewActions/components/StartGradingButton.jsx
@@ -94,7 +94,7 @@ export class StartGradingButton extends React.Component {
           variant="primary"
           iconAfter={args.iconAfter}
           onClick={this.handleClick}
-          disabled={this.props.isPending}
+          disabled={this.props.gradeIsPending || this.props.lockIsPending}
         >
           <FormattedMessage {...args.label} />
         </Button>
@@ -119,11 +119,13 @@ StartGradingButton.propTypes = {
   gradingStatus: PropTypes.string.isRequired,
   startGrading: PropTypes.func.isRequired,
   stopGrading: PropTypes.func.isRequired,
-  isPending: PropTypes.bool.isRequired,
+  gradeIsPending: PropTypes.bool.isRequired,
+  lockIsPending: PropTypes.bool.isRequired,
 };
 
 export const mapStateToProps = (state) => ({
-  isPending: selectors.requests.isPending(state, { requestKey: RequestKeys.submitGrade }),
+  gradeIsPending: selectors.requests.isPending(state, { requestKey: RequestKeys.submitGrade }),
+  lockIsPending: selectors.requests.isPending(state, { requestKey: RequestKeys.setLock }),
   gradeStatus: selectors.grading.selected.gradeStatus(state),
   gradingStatus: selectors.grading.selected.gradingStatus(state),
 });
diff --git a/src/containers/ReviewActions/components/StartGradingButton.test.jsx b/src/containers/ReviewActions/components/StartGradingButton.test.jsx
index 6afef81..2a29d42 100644
--- a/src/containers/ReviewActions/components/StartGradingButton.test.jsx
+++ b/src/containers/ReviewActions/components/StartGradingButton.test.jsx
@@ -36,7 +36,8 @@ let el;
 describe('StartGradingButton component', () => {
   describe('component', () => {
     const props = {
-      isPending: false,
+      gradeIsPending: false,
+      lockIsPending: false,
     };
     beforeEach(() => {
       props.startGrading = jest.fn().mockName('this.props.startGrading');
@@ -69,9 +70,14 @@ describe('StartGradingButton component', () => {
       test('snapshot: ungraded (startGrading callback)', () => {
         expect(mockedEl(statuses.ungraded).instance().render()).toMatchSnapshot();
       });
-      test('snapshot: pending (disabled)', () => {
+      test('snapshot: grade pending (disabled)', () => {
         el = mockedEl(statuses.ungraded);
-        el.setProps({ isPending: true });
+        el.setProps({ gradeIsPending: true });
+        expect(el.instance().render()).toMatchSnapshot();
+      });
+      test('snapshot: lock pending (disabled)', () => {
+        el = mockedEl(statuses.ungraded);
+        el.setProps({ lockIsPending: true });
         expect(el.instance().render()).toMatchSnapshot();
       });
       test('snapshot: graded, confirmOverride (startGrading callback)', () => {
@@ -92,14 +98,22 @@ describe('StartGradingButton component', () => {
     beforeEach(() => {
       mapped = mapStateToProps(testState);
     });
-    test('isPending loads from requests.isPending(submitGrade)', () => {
-      expect(mapped.isPending).toEqual(
+    test('gradeIsPending loads from requests.gradeIsPending(submitGrade)', () => {
+      expect(mapped.gradeIsPending).toEqual(
         selectors.requests.isPending(
           testState,
           { requestKey: RequestKeys.submitGrade },
         ),
       );
     });
+    test('lockIsPending loads from requests.lockIsPending(setLock)', () => {
+      expect(mapped.lockIsPending).toEqual(
+        selectors.requests.isPending(
+          testState,
+          { requestKey: RequestKeys.setLock },
+        ),
+      );
+    });
     test('gradeStatus loads from grading.selected.gradeStatus', () => {
       expect(mapped.gradeStatus).toEqual(selectors.grading.selected.gradeStatus(testState));
     });
diff --git a/src/containers/ReviewActions/components/__snapshots__/StartGradingButton.test.jsx.snap b/src/containers/ReviewActions/components/__snapshots__/StartGradingButton.test.jsx.snap
index be5f631..bff99fc 100644
--- a/src/containers/ReviewActions/components/__snapshots__/StartGradingButton.test.jsx.snap
+++ b/src/containers/ReviewActions/components/__snapshots__/StartGradingButton.test.jsx.snap
@@ -1,5 +1,33 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`StartGradingButton component component snapshotes snapshot: grade pending (disabled) 1`] = `
+<React.Fragment>
+  <Button
+    disabled={true}
+    iconAfter={[MockFunction icons.Highlight]}
+    onClick={[MockFunction this.handleClick]}
+    variant="primary"
+  >
+    <FormattedMessage
+      defaultMessage="Start grading"
+      description="Review pane button text to start grading"
+      id="ora-grading.ReviewActions.StartGradingButton.startGrading"
+    />
+  </Button>
+  <OverrideGradeConfirmModal
+    isOpen={false}
+    onCancel={[MockFunction this.hideConfirmOverrideGrade]}
+    onConfirm={[MockFunction this.confirmOverrideGrade]}
+  />
+  <StopGradingConfirmModal
+    isOpen={false}
+    isOverride={false}
+    onCancel={[MockFunction this.hideConfirmStopGrading]}
+    onConfirm={[MockFunction this.confirmStopGrading]}
+  />
+</React.Fragment>
+`;
+
 exports[`StartGradingButton component component snapshotes snapshot: graded, confirmOverride (startGrading callback) 1`] = `
 <React.Fragment>
   <Button
@@ -56,9 +84,7 @@ exports[`StartGradingButton component component snapshotes snapshot: inProgress,
 </React.Fragment>
 `;
 
-exports[`StartGradingButton component component snapshotes snapshot: locked (null) 1`] = `null`;
-
-exports[`StartGradingButton component component snapshotes snapshot: pending (disabled) 1`] = `
+exports[`StartGradingButton component component snapshotes snapshot: lock pending (disabled) 1`] = `
 <React.Fragment>
   <Button
     disabled={true}
@@ -86,6 +112,8 @@ exports[`StartGradingButton component component snapshotes snapshot: pending (di
 </React.Fragment>
 `;
 
+exports[`StartGradingButton component component snapshotes snapshot: locked (null) 1`] = `null`;
+
 exports[`StartGradingButton component component snapshotes snapshot: ungraded (startGrading callback) 1`] = `
 <React.Fragment>
   <Button
diff --git a/src/containers/ReviewModal/ReviewErrors/LockErrors.jsx b/src/containers/ReviewModal/ReviewErrors/LockErrors.jsx
new file mode 100644
index 0000000..12e49d4
--- /dev/null
+++ b/src/containers/ReviewModal/ReviewErrors/LockErrors.jsx
@@ -0,0 +1,65 @@
+import React from 'react';
+import PropTypes from 'prop-types';
+import { connect } from 'react-redux';
+
+import { FormattedMessage } from '@edx/frontend-platform/i18n';
+
+import { selectors } from 'data/redux';
+import { RequestKeys, ErrorStatuses } from 'data/constants/requests';
+
+import messages from './messages';
+
+import ReviewError from './ReviewError';
+
+/**
+ * <LockErrors />
+ */
+export class LockErrors extends React.Component {
+  get errorProp() {
+    if (this.errorStatus === ErrorStatuses.forbidden) {
+      return {
+        heading: messages.errorLockContestedHeading,
+        message: messages.errorLockContested,
+      };
+    }
+
+    return {
+      heading: messages.errorLockBadRequestHeading,
+      message: messages.errorLockBadRequest,
+    };
+  }
+
+  render() {
+    if (!this.props.isFailed) { return null; }
+    const { heading, message } = this.errorProp;
+    return (
+      <ReviewError
+        key="lockFailed"
+        headingMessage={heading}
+      >
+        <FormattedMessage {...message} />
+      </ReviewError>
+    );
+  }
+}
+LockErrors.defaultProps = {
+  errorStatus: undefined,
+};
+LockErrors.propTypes = {
+  // redux
+  isFailed: PropTypes.bool.isRequired,
+  errorStatus: PropTypes.number,
+};
+
+export const mapStateToProps = (state) => ({
+  isFailed: selectors.requests.isFailed(state, {
+    requestKey: RequestKeys.setLock,
+  }),
+  errorStatus: selectors.requests.errorStatus(state, {
+    requestKey: RequestKeys.setLock,
+  }),
+});
+
+export const mapDispatchToProps = {};
+
+export default connect(mapStateToProps, mapDispatchToProps)(LockErrors);
diff --git a/src/containers/ReviewModal/ReviewErrors/LockErrors.test.jsx b/src/containers/ReviewModal/ReviewErrors/LockErrors.test.jsx
new file mode 100644
index 0000000..9f14b72
--- /dev/null
+++ b/src/containers/ReviewModal/ReviewErrors/LockErrors.test.jsx
@@ -0,0 +1,62 @@
+import React from 'react';
+import { shallow } from 'enzyme';
+
+import { selectors } from 'data/redux';
+import { ErrorStatuses, RequestKeys } from 'data/constants/requests';
+
+import {
+  LockErrors,
+  mapStateToProps,
+} from './LockErrors';
+
+jest.mock('data/redux', () => ({
+  selectors: {
+    requests: {
+      errorStatus: (...args) => ({ errorStatus: args }),
+      isFailed: (...args) => ({ isFailed: args }),
+    },
+  },
+}));
+
+let el;
+jest.mock('./ReviewError', () => 'ReviewError');
+
+const requestKey = RequestKeys.setLock;
+
+describe('LockErrors component', () => {
+  const props = {
+    isFailed: true,
+  };
+  describe('component', () => {
+    beforeEach(() => {
+      el = shallow(<LockErrors {...props} />);
+      el.instance().dismissError = jest.fn().mockName('this.dismissError');
+    });
+    describe('snapshots', () => {
+      test('no failure', () => {
+        el.setProps({ isFailed: false });
+        expect(el.instance().render()).toMatchSnapshot();
+      });
+      test('snapshot: error with bad request', () => {
+        el.setProps({ errorStatus: ErrorStatuses.badRequest });
+        expect(el.instance().render()).toMatchSnapshot();
+      });
+      test('snapshot: error with conflicted lock', () => {
+        el.setProps({ errorStatus: ErrorStatuses.forbidden });
+        expect(el.instance().render()).toMatchSnapshot();
+      });
+    });
+  });
+  describe('mapStateToProps', () => {
+    let mapped;
+    const testState = { some: 'test-state' };
+    beforeEach(() => {
+      mapped = mapStateToProps(testState);
+    });
+    test('errorStatus loads from requests.errorStatus(setLock)', () => {
+      expect(mapped.errorStatus).toEqual(
+        selectors.requests.errorStatus(testState, { requestKey }),
+      );
+    });
+  });
+});
diff --git a/src/containers/ReviewModal/ReviewErrors/ReviewError.jsx b/src/containers/ReviewModal/ReviewErrors/ReviewError.jsx
index 050756a..354165a 100644
--- a/src/containers/ReviewModal/ReviewErrors/ReviewError.jsx
+++ b/src/containers/ReviewModal/ReviewErrors/ReviewError.jsx
@@ -44,6 +44,9 @@ const ReviewError = ({
     </Alert>
   );
 };
+ReviewError.defaultProps = {
+  actions: {},
+};
 ReviewError.propTypes = {
   actions: PropTypes.shape({
     cancel: PropTypes.shape({
@@ -54,7 +57,7 @@ ReviewError.propTypes = {
       onClick: PropTypes.func,
       message: messageShape,
     }),
-  }).isRequired,
+  }),
   headingMessage: messageShape.isRequired,
   children: PropTypes.node.isRequired,
 };
diff --git a/src/containers/ReviewModal/ReviewErrors/__snapshots__/LockErrors.test.jsx.snap b/src/containers/ReviewModal/ReviewErrors/__snapshots__/LockErrors.test.jsx.snap
new file mode 100644
index 0000000..054c91f
--- /dev/null
+++ b/src/containers/ReviewModal/ReviewErrors/__snapshots__/LockErrors.test.jsx.snap
@@ -0,0 +1,39 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`LockErrors component component snapshots no failure 1`] = `null`;
+
+exports[`LockErrors component component snapshots snapshot: error with bad request 1`] = `
+<ReviewError
+  headingMessage={
+    Object {
+      "defaultMessage": "Invalid request. Please check your input.",
+      "description": "Error lock request for missing params",
+      "id": "ora-grading.ReviewModal.errorLockBadRequestHeading",
+    }
+  }
+>
+  <FormattedMessage
+    defaultMessage="Invalid request. Please check your input."
+    description="Error lock request for missing params"
+    id="ora-grading.ReviewModal.errorLockBadRequest"
+  />
+</ReviewError>
+`;
+
+exports[`LockErrors component component snapshots snapshot: error with conflicted lock 1`] = `
+<ReviewError
+  headingMessage={
+    Object {
+      "defaultMessage": "Invalid request. Please check your input.",
+      "description": "Error lock request for missing params",
+      "id": "ora-grading.ReviewModal.errorLockBadRequestHeading",
+    }
+  }
+>
+  <FormattedMessage
+    defaultMessage="Invalid request. Please check your input."
+    description="Error lock request for missing params"
+    id="ora-grading.ReviewModal.errorLockBadRequest"
+  />
+</ReviewError>
+`;
diff --git a/src/containers/ReviewModal/ReviewErrors/__snapshots__/index.test.jsx.snap b/src/containers/ReviewModal/ReviewErrors/__snapshots__/index.test.jsx.snap
index 4bf64fd..44ecc2c 100644
--- a/src/containers/ReviewModal/ReviewErrors/__snapshots__/index.test.jsx.snap
+++ b/src/containers/ReviewModal/ReviewErrors/__snapshots__/index.test.jsx.snap
@@ -4,5 +4,6 @@ exports[`ReviewErrors component component snapshot: no failure 1`] = `
 <Fragment>
   <FetchErrors />
   <SubmitErrors />
+  <LockErrors />
 </Fragment>
 `;
diff --git a/src/containers/ReviewModal/ReviewErrors/index.jsx b/src/containers/ReviewModal/ReviewErrors/index.jsx
index d0852e0..519093e 100644
--- a/src/containers/ReviewModal/ReviewErrors/index.jsx
+++ b/src/containers/ReviewModal/ReviewErrors/index.jsx
@@ -1,6 +1,7 @@
 import React from 'react';
 
 import FetchErrors from './FetchErrors';
+import LockErrors from './LockErrors';
 import SubmitErrors from './SubmitErrors';
 
 /**
@@ -10,6 +11,7 @@ export const ReviewErrors = () => (
   <>
     <FetchErrors />
     <SubmitErrors />
+    <LockErrors />
   </>
 );
 ReviewErrors.defaultProps = {
diff --git a/src/containers/ReviewModal/ReviewErrors/index.test.jsx b/src/containers/ReviewModal/ReviewErrors/index.test.jsx
index 4e11d18..6aa4903 100644
--- a/src/containers/ReviewModal/ReviewErrors/index.test.jsx
+++ b/src/containers/ReviewModal/ReviewErrors/index.test.jsx
@@ -5,6 +5,7 @@ import { ReviewErrors } from '.';
 
 jest.mock('./FetchErrors', () => 'FetchErrors');
 jest.mock('./SubmitErrors', () => 'SubmitErrors');
+jest.mock('./LockErrors', () => 'LockErrors');
 
 describe('ReviewErrors component', () => {
   describe('component', () => {
diff --git a/src/containers/ReviewModal/ReviewErrors/messages.js b/src/containers/ReviewModal/ReviewErrors/messages.js
index 56b165d..c37b112 100644
--- a/src/containers/ReviewModal/ReviewErrors/messages.js
+++ b/src/containers/ReviewModal/ReviewErrors/messages.js
@@ -47,7 +47,26 @@ const messages = defineMessages({
     defaultMessage: 'It looks like someone else got here first!  Your grade submission has been rejected',
     description: 'Error Submitting Grade content',
   },
-
+  errorLockContestedHeading: {
+    id: 'ora-grading.ReviewModal.errorLockContestedHeading',
+    defaultMessage: 'The lock owned by another user',
+    description: 'Error lock by someone else',
+  },
+  errorLockContested: {
+    id: 'ora-grading.ReviewModal.errorLockContested',
+    defaultMessage: 'The lock owned by another user',
+    description: 'Error lock by someone else',
+  },
+  errorLockBadRequestHeading: {
+    id: 'ora-grading.ReviewModal.errorLockBadRequestHeading',
+    defaultMessage: 'Invalid request. Please check your input.',
+    description: 'Error lock request for missing params',
+  },
+  errorLockBadRequest: {
+    id: 'ora-grading.ReviewModal.errorLockBadRequest',
+    defaultMessage: 'Invalid request. Please check your input.',
+    description: 'Error lock request for missing params',
+  },
 });
 
 export default StrictDict(messages);
diff --git a/src/containers/Rubric/__snapshots__/index.test.jsx.snap b/src/containers/Rubric/__snapshots__/index.test.jsx.snap
index 1fad1cb..d3d166d 100644
--- a/src/containers/Rubric/__snapshots__/index.test.jsx.snap
+++ b/src/containers/Rubric/__snapshots__/index.test.jsx.snap
@@ -47,6 +47,7 @@ exports[`Rubric Container snapshot is grading 1`] = `
       disabledStates={
         Array [
           "pending",
+          "complete",
         ]
       }
       labels={
@@ -75,6 +76,82 @@ exports[`Rubric Container snapshot is grading 1`] = `
 </Card>
 `;
 
+exports[`Rubric Container snapshot is grading, lock is pending 1`] = `
+<Card
+  className="grading-rubric-card"
+>
+  <Card.Body
+    className="grading-rubric-body"
+  >
+    <h3>
+      <FormattedMessage
+        defaultMessage="Rubric"
+        description="Rubric interface label"
+        id="ora-grading.Rubric.rubric"
+      />
+    </h3>
+    <hr
+      className="m-2.5"
+    />
+    <CriterionContainer
+      isGrading={true}
+      orderNum={1}
+    />
+    <CriterionContainer
+      isGrading={true}
+      orderNum={2}
+    />
+    <CriterionContainer
+      isGrading={true}
+      orderNum={3}
+    />
+    <CriterionContainer
+      isGrading={true}
+      orderNum={4}
+    />
+    <CriterionContainer
+      isGrading={true}
+      orderNum={5}
+    />
+    <hr />
+    <RubricFeedback />
+  </Card.Body>
+  <div
+    className="grading-rubric-footer"
+  >
+    <StatefulButton
+      disabledStates={
+        Array [
+          "pending",
+          "complete",
+        ]
+      }
+      labels={
+        Object {
+          "complete": <FormattedMessage
+            defaultMessage="Grade Submitted"
+            description="Submit Grade button text after successful submission"
+            id="ora-grading.Rubric.gradeSubmitted"
+          />,
+          "default": <FormattedMessage
+            defaultMessage="Submit grade"
+            description="Submit Grade button text"
+            id="ora-grading.Rubric.submitGrade"
+          />,
+          "pending": <FormattedMessage
+            defaultMessage="Submitting grade"
+            description="Submit Grade button text while submitting"
+            id="ora-grading.Rubric.submittingGrade"
+          />,
+        }
+      }
+      onClick={[MockFunction this.submitGradeHandler]}
+      state="pending"
+    />
+  </div>
+</Card>
+`;
+
 exports[`Rubric Container snapshot is grading, submit pending 1`] = `
 <Card
   className="grading-rubric-card"
@@ -122,6 +199,7 @@ exports[`Rubric Container snapshot is grading, submit pending 1`] = `
       disabledStates={
         Array [
           "pending",
+          "complete",
         ]
       }
       labels={
@@ -240,6 +318,7 @@ exports[`Rubric Container snapshot submit completed 1`] = `
       disabledStates={
         Array [
           "pending",
+          "complete",
         ]
       }
       labels={
diff --git a/src/containers/Rubric/index.jsx b/src/containers/Rubric/index.jsx
index 4c2a8ac..aabcde1 100644
--- a/src/containers/Rubric/index.jsx
+++ b/src/containers/Rubric/index.jsx
@@ -33,7 +33,7 @@ export class Rubric extends React.Component {
   }
 
   get submitButtonState() {
-    if (this.props.isPending) {
+    if (this.props.gradeIsPending || this.props.lockIsPending) {
       return ButtonStates.pending;
     }
     if (this.props.isCompleted) {
@@ -68,7 +68,7 @@ export class Rubric extends React.Component {
             <StatefulButton
               onClick={this.submitGradeHandler}
               state={this.submitButtonState}
-              disabledStates={[ButtonStates.pending]}
+              disabledStates={[ButtonStates.pending, ButtonStates.complete]}
               labels={{
                 [ButtonStates.default]: <FormattedMessage {...messages.submitGrade} />,
                 [ButtonStates.pending]: <FormattedMessage {...messages.submittingGrade} />,
@@ -87,17 +87,17 @@ Rubric.defaultProps = {
 Rubric.propTypes = {
   isCompleted: PropTypes.bool.isRequired,
   isGrading: PropTypes.bool.isRequired,
-  isPending: PropTypes.bool.isRequired,
+  gradeIsPending: PropTypes.bool.isRequired,
+  lockIsPending: PropTypes.bool.isRequired,
   criteriaIndices: PropTypes.arrayOf(PropTypes.number),
   submitGrade: PropTypes.func.isRequired,
 };
 
-const requestKey = RequestKeys.submitGrade;
-
 export const mapStateToProps = (state) => ({
-  isCompleted: selectors.requests.isCompleted(state, { requestKey }),
+  isCompleted: selectors.requests.isCompleted(state, { requestKey: RequestKeys.submitGrade }),
   isGrading: selectors.grading.selected.isGrading(state),
-  isPending: selectors.requests.isPending(state, { requestKey }),
+  gradeIsPending: selectors.requests.isPending(state, { requestKey: RequestKeys.submitGrade }),
+  lockIsPending: selectors.requests.isPending(state, { requestKey: RequestKeys.setLock }),
   criteriaIndices: selectors.app.rubric.criteriaIndices(state),
 });
 
diff --git a/src/containers/Rubric/index.test.jsx b/src/containers/Rubric/index.test.jsx
index da7c19d..24aabb7 100644
--- a/src/containers/Rubric/index.test.jsx
+++ b/src/containers/Rubric/index.test.jsx
@@ -2,6 +2,7 @@ import React from 'react';
 import { shallow } from 'enzyme';
 
 import { selectors, thunkActions } from 'data/redux';
+import { RequestKeys } from 'data/constants/requests';
 import { Rubric, mapStateToProps, mapDispatchToProps } from '.';
 
 jest.mock('containers/CriterionContainer', () => 'CriterionContainer');
@@ -36,7 +37,8 @@ jest.mock('data/redux', () => ({
 describe('Rubric Container', () => {
   const props = {
     isCompleted: false,
-    isPending: false,
+    gradeIsPending: false,
+    lockIsPending: false,
     isGrading: true,
     criteriaIndices: [1, 2, 3, 4, 5],
     submitGrade: jest.fn().mockName('this.props.submitGrade'),
@@ -60,7 +62,11 @@ describe('Rubric Container', () => {
       expect(el.instance().render()).toMatchSnapshot();
     });
     test('is grading, submit pending', () => {
-      el.setProps({ isPending: true });
+      el.setProps({ gradeIsPending: true });
+      expect(el.instance().render()).toMatchSnapshot();
+    });
+    test('is grading, lock is pending', () => {
+      el.setProps({ lockIsPending: true });
       expect(el.instance().render()).toMatchSnapshot();
     });
     test('submit completed', () => {
@@ -111,6 +117,16 @@ describe('Rubric Container', () => {
     test('isGrading from selectors.grading.selected.isGrading', () => {
       expect(mapped.isGrading).toEqual(selectors.grading.selected.isGrading(testState));
     });
+    test('gradeIsPending from selectors.requests.isPending(submitGrade)', () => {
+      expect(mapped.gradeIsPending).toEqual(
+        selectors.requests.isPending(testState, { requestKey: RequestKeys.submitGrade }),
+      );
+    });
+    test('lockIsPending from selectors.requests.isPending(setLock)', () => {
+      expect(mapped.lockIsPending).toEqual(selectors.requests.isPending(
+        testState, { requestKey: RequestKeys.setLock },
+      ));
+    });
     test('criteriaIndices from selectors.app.rubric.criteriaIndices', () => {
       expect(mapped.criteriaIndices).toEqual(
         selectors.app.rubric.criteriaIndices(testState),
diff --git a/src/data/redux/grading/reducer.js b/src/data/redux/grading/reducer.js
index efd0b72..375d2af 100644
--- a/src/data/redux/grading/reducer.js
+++ b/src/data/redux/grading/reducer.js
@@ -166,6 +166,10 @@ const grading = createSlice({
         gradingData,
       };
     },
+    failSetLock: (state, { payload }) => ({
+      ...state,
+      current: { ...state.current, lockStatus: payload.lockStatus },
+    }),
     setRubricFeedback: (state, { payload }) => (
       updateGradingData(state, { overallFeedback: payload })
     ),
diff --git a/src/data/redux/thunkActions/grading.js b/src/data/redux/thunkActions/grading.js
index 585eda7..a1fdd6c 100644
--- a/src/data/redux/thunkActions/grading.js
+++ b/src/data/redux/thunkActions/grading.js
@@ -72,6 +72,11 @@ export const startGrading = () => (dispatch, getState) => {
       }
       dispatch(actions.grading.startGrading({ ...response, gradeData }));
     },
+    onFailure: (error) => {
+      if (error.response.status === ErrorStatuses.forbidden) {
+        dispatch(actions.grading.failSetLock(error.response.data));
+      }
+    },
   }));
 };
 
@@ -87,6 +92,11 @@ export const cancelGrading = () => (dispatch, getState) => {
     onSuccess: () => {
       dispatch(module.stopGrading());
     },
+    onFailure: (error) => {
+      if (error.response.status === ErrorStatuses.forbidden) {
+        dispatch(actions.grading.failSetLock(error.response.data));
+      }
+    },
   }));
 };
 
diff --git a/src/data/services/lms/fakeData/testUtils.js b/src/data/services/lms/fakeData/testUtils.js
index 55529ec..45e187e 100644
--- a/src/data/services/lms/fakeData/testUtils.js
+++ b/src/data/services/lms/fakeData/testUtils.js
@@ -67,6 +67,21 @@ export const genTestUtils = ({ dispatch }) => {
         },
       ),
     }),
+    setLock: StrictDict({
+      start: mockStart(RequestKeys.setLock),
+      success: () => {
+        dispatch(actions.requests.completeRequest({
+          requestKey: RequestKeys.setLock,
+          response: {
+            lockStatus: lockStatuses.inProgress,
+          },
+        }));
+      },
+      badRequestError: mockError(RequestKeys.setLock, ErrorStatuses.badRequest),
+      contestedLockError: mockError(RequestKeys.setLock, ErrorStatuses.forbidden, {
+        lockStatus: lockStatuses.locked,
+      }),
+    }),
   };
 };