You can check https://console.cloud.google.com/errors for any errors.
I got 502 error too. For my case, I got ModuleNotFoundError: No module named ‘mysite' from google cloud error. I solved it by changing my /main.py which I copied exactly from this tutorial. I changed the first line.
Great again! thanks a lot very helpful!
I have question regarding the two databases: If a change is made (I mean just a row insertions not modifications on models) when working on the local sqlite, it will not be reflected in later pushes on the Postgre, right? So we will end up with potentially different databases.
I thunk it would be a good idea to point out that the exact command will depend on your operating system. Google provides different commands for different OSes. See, for example, https://cloud.google.com/sql/docs/mysql/quickstart-proxy-test#install-proxy