This page describes what you need to do in order to upgrade to MyPet 3.0
If you are running MyPet-NPC too you can delete that now as it is included into MyPet itself.
If you never touched the skilltrees you can skip this step!
If you made your own skilltrees or edited the default ones you need to convert them to the new format using the following steps:
Import Legacy Skilltree
.st.jsonfiles to the skilltrees folder on your server
MyPet doesn't support numeric item IDs anymore. All settings that requires an config item will require the 1.13 item ID even if you don't run a 1.13 server