- Can't add companion to journal or collection
- Error when attempting to learn pet
- Purchased a pet in the auction house that gives the message "Can't add companion to your account."
If you cannot add a companion to your pet collection check the following.
To learn a pet, you must have at least another pet of the same level or higher.
You cannot learn a level 25 pet if you don't have at least one level 25 pet of your own.
If you caged your only level 25 pet, you won't be able to uncage it until you have levelled a different pet to 25.
Too Many Pets
Your collection can hold up to 1000 pets in total, and only up to 3 of each type.
If you complete the Battle on the Broken Isles achievement, you will the receive Pocket Pet Portal item which sets the total maximum for your pet collection to 1500. If you already increased your cap to 1500, you can increase it to 2000 by purchasing the Interdimensional Pet Portal from your Battle for Azeroth pet vendor for 1000 Polished Pet Charms.
Once at a cap, you must cage or release pets before you can add more.
To be caged or released, pets must be at full-heath and not assigned to a battle slot. To cage or release pets, open your Collections (Shift-P) and click on the Pet Journal tab at the bottom.
Pets captured in the wild can only be released. Locate the pet in the left pane, right-click, and select Release. Most other pets can be caged by right-clicking and selecting Put In Cage.