diff --git a/app/assets/javascripts/boards/components/issue_card_inner.vue b/app/assets/javascripts/boards/components/issue_card_inner.vue
index 7f7510545c6695503279b8fda5d57f7a5484d422..0e0d1e64f4afe898d93702d2daaadd0cd0575a11 100644
--- a/app/assets/javascripts/boards/components/issue_card_inner.vue
+++ b/app/assets/javascripts/boards/components/issue_card_inner.vue
@@ -233,7 +233,7 @@ export default {
           :key="assignee.id"
           :link-href="assigneeUrl(assignee)"
           :img-alt="avatarUrlTitle(assignee)"
-          :img-src="assignee.avatar"
+          :img-src="assignee.avatar || assignee.avatar_url"
           :img-size="24"
           class="js-no-trigger"
           tooltip-placement="bottom"
diff --git a/changelogs/unreleased/197894.yml b/changelogs/unreleased/197894.yml
new file mode 100644
index 0000000000000000000000000000000000000000..7cdcdf4be95d17ac67bab5502eae648d2801d0f8
--- /dev/null
+++ b/changelogs/unreleased/197894.yml
@@ -0,0 +1,5 @@
+---
+title: MVC for assignees avatar dissapearing when opening issue sidebar in board
+merge_request:
+author: Oregand
+type: fixed
diff --git a/spec/frontend/boards/issue_card_spec.js b/spec/frontend/boards/issue_card_spec.js
index 08cffed5f00664c12c048a771361907b063bc785..526cdb81ac6e5ab501474adb48020556e4c50873 100644
--- a/spec/frontend/boards/issue_card_spec.js
+++ b/spec/frontend/boards/issue_card_spec.js
@@ -97,6 +97,9 @@ describe('Issue card component', () => {
           issue: {
             ...wrapper.props('issue'),
             assignees: [user],
+            updateData(newData) {
+              Object.assign(this, newData);
+            },
           },
         });
 
@@ -118,6 +121,28 @@ describe('Issue card component', () => {
       it('renders avatar', () => {
         expect(wrapper.find('.board-card-assignee img').exists()).toBe(true);
       });
+
+      it('renders the avatar using avatar_url property', done => {
+        wrapper.props('issue').updateData({
+          ...wrapper.props('issue'),
+          assignees: [
+            {
+              id: '1',
+              name: 'test',
+              state: 'active',
+              username: 'test_name',
+              avatar_url: 'test_image_from_avatar_url',
+            },
+          ],
+        });
+
+        wrapper.vm.$nextTick(() => {
+          expect(wrapper.find('.board-card-assignee img').attributes('src')).toBe(
+            'test_image_from_avatar_url?width=24',
+          );
+          done();
+        });
+      });
     });
 
     describe('assignee default avatar', () => {