when i tried to import tracks to playlists, a lot of error messages appeared

Great find, thank you!

I've added this to the roadmap and subscribed you:

https://support.mixo.dj/t/drag-drop-import-type

This has been fixed in an earlier release:

v0.13

The current release is v0.15.



Download the latest version in App or via https://beta.mixo.dj.