Can't Add Pet to Journal with Error "Can't Add Companion"

This error will appear if the pet is already present in the collection.  Please check your Retail collection, it only allows three total copies of a pet.  If you are playing classic you can only learn each pet once.

If you do not already have a copy of the pet, please submit a new Bug Report.

Note: Bugs submitted in-game do not receive a personal response. Instead, they'll be directed to the teams responsible for addressing them.