Hey friends, I hope this helps someone not spend a few hours tracking down this issue like I did. Due to the recently released CVE-2022-32224, I needed to update our version of Rails to the proper version, 6.1.6.1. However when I did so, I started getting the following exception all over my code with a very unhelpful stack trace:
Psych::DisallowedClass: Tried to load unspecified class: Symbol
Sadly, searching did not turn up any useful leads. Only when I thought to go look at the commit in the rails code itself, did the solution become apparent.
I needed to add Symbol to the allowed YAML safe load classes in my environment files like this:
ActiveRecord.yaml_column_permitted_classes = [Symbol]
I hope this can help someone else.