12.9 upgrade issue: Service Templates - 500 Error - NoMethodError (undefined method `instance?' for #<AlertsService:0x00007f6c61115d80>
Summary
After upgrading to 12.9.3 getting a 500 Error when accessing /admin/application_settings/services with the following stack trace logged in production.log:
Started GET "/admin/application_settings/services" for 10.208.53.76 at 2020-04-17 11:04:05 -0400
Completed 500 Internal Server Error in 121ms (ActiveRecord: 25.5ms | Elasticsearch: 0.0ms | Allocations: 10894)
NoMethodError (undefined method `instance?' for #<AlertsService:0x00007f6c130861b0>
Did you mean? instance_of?):
app/models/service.rb:39:in `block in <class:Service>'
app/controllers/admin/services_controller.rb:37:in `block in services_templates'
app/controllers/admin/services_controller.rb:35:in `map'
app/controllers/admin/services_controller.rb:35:in `services_templates'
app/controllers/admin/services_controller.rb:10:in `index'
app/controllers/application_controller.rb:479:in `set_current_admin'
lib/gitlab/session.rb:11:in `with_session'
app/controllers/application_controller.rb:470:in `set_session_storage'
lib/gitlab/i18n.rb:55:in `with_locale'
lib/gitlab/i18n.rb:61:in `with_user_locale'
app/controllers/application_controller.rb:464:in `set_locale'
lib/gitlab/error_tracking.rb:34:in `with_context'
app/controllers/application_controller.rb:555:in `sentry_context'
lib/gitlab/application_context.rb:46:in `block in use'
lib/gitlab/application_context.rb:46:in `use'
lib/gitlab/application_context.rb:19:in `with_context'
app/controllers/application_controller.rb:455:in `set_current_context'
lib/gitlab/middleware/rails_queue_duration.rb:27:in `call'
lib/gitlab/metrics/rack_middleware.rb:17:in `block in call'
lib/gitlab/metrics/transaction.rb:62:in `run'
lib/gitlab/metrics/rack_middleware.rb:17:in `call'
lib/gitlab/request_profiler/middleware.rb:17:in `call'
lib/gitlab/middleware/go.rb:20:in `call'
lib/gitlab/etag_caching/middleware.rb:13:in `call'
lib/gitlab/middleware/multipart.rb:122:in `call'
lib/gitlab/middleware/read_only/controller.rb:53:in `call'
lib/gitlab/middleware/read_only.rb:18:in `call'
lib/gitlab/middleware/basic_health_check.rb:25:in `call'
lib/gitlab/middleware/request_context.rb:23:in `call'
config/initializers/fix_local_cache_middleware.rb:9:in `call'
lib/gitlab/metrics/requests_rack_middleware.rb:49:in `call'
lib/gitlab/middleware/release_env.rb:12:in `call'
Also see someone else had same issue: https://www.reddit.com/r/gitlab/comments/g2c2hb/service_templates_admin_returns_500/
~bug GitLab Core
Edited by Chris Denneen