diff --git a/app/assets/javascripts/lib/utils/common_utils.js b/app/assets/javascripts/lib/utils/common_utils.js
index 128ef5b335e6fa3f11d4ce6855f236b8093ef646..a41e43780bc749ad1516f331b822a46dbb3be3f7 100644
--- a/app/assets/javascripts/lib/utils/common_utils.js
+++ b/app/assets/javascripts/lib/utils/common_utils.js
@@ -45,6 +45,7 @@ export const checkPageAndAction = (page, action) => {
 
 export const isInIncidentPage = () => checkPageAndAction('incidents', 'show');
 export const isInIssuePage = () => checkPageAndAction('issues', 'show');
+export const isInDesignPage = () => checkPageAndAction('issues', 'designs');
 export const isInMRPage = () => checkPageAndAction('merge_requests', 'show');
 export const isInEpicPage = () => checkPageAndAction('epics', 'show');
 
diff --git a/app/assets/javascripts/sidebar/mount_sidebar.js b/app/assets/javascripts/sidebar/mount_sidebar.js
index 2760bf431eaaac994d27b5a1ca91e932d0ae6d25..f2ba0085df6caf2d3273ca281270f43b1333e52a 100644
--- a/app/assets/javascripts/sidebar/mount_sidebar.js
+++ b/app/assets/javascripts/sidebar/mount_sidebar.js
@@ -14,7 +14,12 @@ import SidebarSeverity from './components/severity/sidebar_severity.vue';
 import Translate from '../vue_shared/translate';
 import CopyEmailToClipboard from './components/copy_email_to_clipboard.vue';
 import createDefaultClient from '~/lib/graphql';
-import { isInIssuePage, isInIncidentPage, parseBoolean } from '~/lib/utils/common_utils';
+import {
+  isInIssuePage,
+  isInDesignPage,
+  isInIncidentPage,
+  parseBoolean,
+} from '~/lib/utils/common_utils';
 import createFlash from '~/flash';
 import { __ } from '~/locale';
 
@@ -49,7 +54,8 @@ function mountAssigneesComponent(mediator) {
           projectPath: fullPath,
           field: el.dataset.field,
           signedIn: el.hasAttribute('data-signed-in'),
-          issuableType: isInIssuePage() || isInIncidentPage() ? 'issue' : 'merge_request',
+          issuableType:
+            isInIssuePage() || isInIncidentPage() || isInDesignPage() ? 'issue' : 'merge_request',
         },
       }),
   });
@@ -78,7 +84,7 @@ function mountReviewersComponent(mediator) {
           issuableIid: String(iid),
           projectPath: fullPath,
           field: el.dataset.field,
-          issuableType: isInIssuePage() ? 'issue' : 'merge_request',
+          issuableType: isInIssuePage() || isInDesignPage() ? 'issue' : 'merge_request',
         },
       }),
   });
diff --git a/changelogs/unreleased/299457-user-cannot-merge-an-issue.yml b/changelogs/unreleased/299457-user-cannot-merge-an-issue.yml
new file mode 100644
index 0000000000000000000000000000000000000000..20ca2c6cc38aae03aea6c7fd5436380fe7c05a84
--- /dev/null
+++ b/changelogs/unreleased/299457-user-cannot-merge-an-issue.yml
@@ -0,0 +1,5 @@
+---
+title: 'Resolve User cannot merge an issue'
+merge_request: 52311
+author:
+type: fixed