I was testing some App Engine things today on one of our internal projects and ran into an interesting senario I had not seen before. If you use App Engine’s git push-to-deploy and you make changes to your builtins in app.yaml, this will not get reflected in the updated running configuration.

In my case, I was getting 404’s when using /_ah/queue/deferred.

The fix for this is to just do the usual appcfg.py update to push the build and this immediately fixes the issue.

I looked around and didn’t come across many results of people having this problem I did find an existing open ticket, Issue 10139: app.yaml builtins return 404 after push-to-deploy for this, so if you’re have the same issue give it a star or leave some feedback on the ticket with any relevent information.