Versioning with endpoint V2 on GAE

Question

I have the live version of my app deployed with its endpoints (no problem with that). I also want to easily be able to test other versions (e.g. staging).

With e

Answer 1

The short answer for me was: do not reuse version names that were previously used with endpointV1.

E.g. I had a testing-dot-MYPROJECT.appspot.com.

I now use a different version: test-dot-MYPROJECT.appspot.com.

For the long answer, have a look at cputoaster's answer.