Merge branch '48976-rails5-invalid-single-table-inheritance-type-group-is-not-a-subclass-of-gitlab-backgroundmigration-fixcrossprojectlabellinks-namespace' into 'master'

Resolve "[Rails5] Invalid single-table inheritance type: Group is not a subclass of Gitlab::BackgroundMigration::FixCrossProjectLabelLinks::Namespace"

Closes #48976

See merge request gitlab-org/gitlab-ce!20462

2 files changed, 8 insertions, 0 deletions

diff --git a/changelogs/unreleased/48976-rails5-invalid-single-table-inheritance-type-group-is-not-a-subclass-of-gitlab-backgroundmigration-fixcrossprojectlabellinks-namespace.yml b/changelogs/unreleased/48976-rails5-invalid-single-table-inheritance-type-group-is-not-a-subclass-of-gitlab-backgroundmigration-fixcrossprojectlabellinks-namespace.yml
new file mode 100644
index 00000000000..e95536b213c
--- /dev/null
+++ b/changelogs/unreleased/48976-rails5-invalid-single-table-inheritance-type-group-is-not-a-subclass-of-gitlab-backgroundmigration-fixcrossprojectlabellinks-namespace.yml
@@ -0,0 +1,6 @@
+---
+title: "[Rails5] Fix 'Invalid single-table inheritance type: Group is not a subclass
+  of Gitlab::BackgroundMigration::FixCrossProjectLabelLinks::Namespace'"
+merge_request: 20462
+author: "@blackst0ne"
+type: fixed
diff --git a/lib/gitlab/background_migration/fix_cross_project_label_links.rb b/lib/gitlab/background_migration/fix_cross_project_label_links.rb
index fa68ba5cca7..0a12401c35f 100644
--- a/lib/gitlab/background_migration/fix_cross_project_label_links.rb
+++ b/lib/gitlab/background_migration/fix_cross_project_label_links.rb
@@ -11,6 +11,7 @@ module Gitlab
       end
 
       class Label < ActiveRecord::Base
+        self.inheritance_column = :_type_disabled
         self.table_name = 'labels'
       end
 
@@ -27,6 +28,7 @@ module Gitlab
       end
 
       class Namespace < ActiveRecord::Base
+        self.inheritance_column = :_type_disabled
         self.table_name = 'namespaces'
 
         def self.groups_with_descendants_ids(start_id, stop_id)