[cowsandmilk]

> Why do they do non-critical changes in production before testing in a stage environment?

I guess the noncritical change here was the change to the database? My experience has been a lot of teams do a poor job having a faithful replica of databases in stage environments to expose this type of issue.

[brookst]

In part because it is somewhere between really hard and impossible. Is your staging DB going to be as big? Seeing the same RPS as prod? Seeing the same scenarios?

Permissions stuff might be caught without a completely faithful replica, but there are always going to be attributes of the system that only exist in prod.