GITHUB_CLIENT_ID and GITHUB_CLIENT_SECRET aren't set on the Heroku treeherder-prod app. Are we using different values for each environment? If so, could you generate some new ones for Heroku prod and set them? Otherwise I can just copy those from Heroku stage. Thanks :-)
I have separate ones for stage and prod, which I think could just be transferred over from the scl3 values. I've updated them on heroku prod now.
Ah I was confused since SCL3 stage wasn't using the same set as Heroku stage (it turns out it was using SCL3 prod's). I've now also changed Heroku stage's to match SCL3 stage's.