Google App Engine session loses attribute

Question

I have an application that stores session authorization details that has been working for years, now the session attribute is returning null. I retrieve the session data at

Answer 1

Could be unrelated as I'm developing in Python/Flask, but I was losing my sessions as I had incorrectly set the application "secret key" to something randomly generated on each instance. This meant as the user was transferred from instance to instance the session was unable to be accessed as each instance had a different key it was signing cookies/sessions with.