This fix is related to the new Hash serialization. The error itself looks like this:
Completed 500 Internal Server Error in 129ms (ActiveRecord: 22.2ms) Psych::DisallowedClass (Tried to load unspecified class: ActionController::Parameters):
And it is related to:
For the plugin to work correctly, you need to make changes in the following file of the Redmine itself. Please open config/application.rb. Go to line 35. Add into:
the following line
Don't forget to add a comma above. It looks like this:
config.active_record.yaml_column_permitted_classes = [ Symbol, ActiveSupport::HashWithIndifferentAccess, ActionController::Parameters ]
Save change. Restart your Redmine.