The warning about not setting whodunnit

After upgrading to PaperTrail 5, you see this warning:

user_for_paper_trail is present, but whodunnit has not been set. PaperTrail no longer adds the set_paper_trail_whodunnit before_action for you. Please add this before_action to your ApplicationController to continue recording whodunnit.

You want to track whodunnit

Add before_action :set_paper_trail_whodunnit to your ApplicationController. See the PaperTrail readme for an example (https://github.com/paper-trail-gem/paper_trail#4a-finding-out-who-was-responsible-for-a-change).

You don't want to track whodunnit

If you no longer want to track whodunnit, you may disable this warning by overriding user_for_paper_trail to return nil.

ruby

# in application_controller.rb
def user_for_paper_trail
  nil # disable whodunnit tracking
end

You just want the warning to go away

Upgrade to PT 6.

Why does PT no longer add this callback for me?

So that you can control the order of callbacks. Maybe you have another callback that must happen first, before set_paper_trail_whodunnit.