Return specfic error message when moving an issue

ee/app/graphql/ee/mutations/boards/issues/issue_move_list.rb

@@ -21,10 +21,9 @@ module EE
             super
           rescue ::Issues::BaseService::EpicAssignmentError => e
             issue.errors.add(:epic_issue, e.message)
-          # because we can't be sure if these exceptions were raised because of epic
-          # we return just a generic error here for now
-          # https://gitlab.com/gitlab-org/gitlab/-/issues/247096
-          rescue ::Gitlab::Access::AccessDeniedError, ActiveRecord::RecordNotFound
+          rescue ::Gitlab::Access::AccessDeniedError
+            issue.errors.add(:base, 'You are not allowed to move the issue')
+          rescue ActiveRecord::RecordNotFound
             issue.errors.add(:base, 'Resource not found')
           end
 

ee/changelogs/unreleased/epic-errmsg.yml

+---
+title: Return more specific error message when moving issue in GraphQL API
+merge_request: 44296
+author:
+type: changed

ee/spec/requests/api/graphql/mutations/boards/issues/issue_move_list_spec.rb

@@ -36,7 +36,7 @@ RSpec.describe 'Reposition and move issue within board lists' do
     project.add_maintainer(user)
   end
 
-  context 'when user has access to the epic' do
+  context 'when user can admin epic' do
     before do
       group.add_maintainer(user)
     end
@@ -81,7 +81,7 @@ RSpec.describe 'Reposition and move issue within board lists' do
       post_graphql_mutation(mutation(params), current_user: user)
 
       mutation_response = graphql_mutation_response(:issue_move_list)
-      expect(mutation_response['errors']).to eq(['Resource not found'])
+      expect(mutation_response['errors']).to eq(['You are not allowed to move the issue'])
       expect(mutation_response['issue']['epic']).to eq(nil)
       expect(mutation_response['issue']['relativePosition']).to eq(3)
     end