"MAC is invalid" 500 Error when upgrading from 2.01 to 2.1

Noticed that in ../config/app.php the APP_KEY was set to "SomeRandomString" as in the screenshot below. I'm assuming all did not go well with installation/update?

I changed it to the app_key value as found in .env, but nothing's working still.

dfRdomString.PNG923x290 12.6 KB