Can't bake object with multiple instances

[dodo522]

Hi, so I got three boxes that share a same object data(I use Alt+D), and the object data has two materials, but I can't bake LightMap no matter how,I will always got some same error:

or:

here's my blender file:
https://drive.google.com/file/d/1lzOsG-3XleivkVDBf8JdLrISPC0ky0B1/view?usp=share_link

[Naxela]

Hi, sorry I didn't see your message before now.

Currently the lightmapper doesn't support object instances, since they need to have unique material data per object, so currently I recommend turning them into single-user objects (Object > Relations > Make single user)