diff --git a/app/services/merge_requests/post_merge_service.rb b/app/services/merge_requests/post_merge_service.rb
index 5b160ffba67..7606d68ff29 100644
--- a/app/services/merge_requests/post_merge_service.rb
+++ b/app/services/merge_requests/post_merge_service.rb
@@ -6,9 +6,9 @@ module MergeRequests
   #
   class PostMergeService < MergeRequests::BaseService
     def execute(merge_request)
+      merge_request.mark_as_merged
       close_issues(merge_request)
       todo_service.merge_merge_request(merge_request, current_user)
-      merge_request.mark_as_merged
       create_event(merge_request)
       create_note(merge_request)
       notification_service.merge_mr(merge_request, current_user)
diff --git a/changelogs/unreleased/osw-mark-as-merged-as-first-post-merge-action.yml b/changelogs/unreleased/osw-mark-as-merged-as-first-post-merge-action.yml
new file mode 100644
index 00000000000..2049afc3d44
--- /dev/null
+++ b/changelogs/unreleased/osw-mark-as-merged-as-first-post-merge-action.yml
@@ -0,0 +1,5 @@
+---
+title: Mark MR as merged regardless of errors when closing issues
+merge_request:
+author:
+type: fixed
diff --git a/spec/services/merge_requests/post_merge_service_spec.rb b/spec/services/merge_requests/post_merge_service_spec.rb
index 790ecce8ded..46e4e3559dc 100644
--- a/spec/services/merge_requests/post_merge_service_spec.rb
+++ b/spec/services/merge_requests/post_merge_service_spec.rb
@@ -47,5 +47,18 @@ describe MergeRequests::PostMergeService do
 
       expect(diff_removal_service).to have_received(:execute)
     end
+
+    it 'marks MR as merged regardless of errors when closing issues' do
+      merge_request.update(target_branch: 'foo')
+      allow(project).to receive(:default_branch).and_return('foo')
+
+      issue = create(:issue, project: project)
+      allow(merge_request).to receive(:closes_issues).and_return([issue])
+      allow_any_instance_of(Issues::CloseService).to receive(:execute).with(issue, commit: merge_request).and_raise
+
+      expect { described_class.new(project, user, {}).execute(merge_request) }.to raise_error
+
+      expect(merge_request.reload).to be_merged
+    end
   end
 end