I have added some colleagues as testers in my Facebook app (I don't want to make it public yet). They look correct in the Facebook app dashboard, but when I try to access the app, I get an error
App Not Setup: This app is still in development mode, and you don't have access to it. Switch to a registered test user or ask an app admin for permissions.
I have tried to figure if there's something wrong with my setup, including
- use the app via https, not http
- ensured the user I'm testing the app with is a developer in Facebook, not a regular (non-developer) user
The proposals about making the app public are not suitable, as we wish not to make the app available to the world.