Søren I haven't been able to reproduce this in 3.8.63. Does it only happen in a single project? If so, it would be great if you could share the project to contact@esotericsoftware.com so we can take a look at it. Sorry for the trouble!
Nate Spine wasn't able to read the image files you see in the log. The message isn't very good though, we'll improve that. Do these images appear in the viewport?
warmanw I see images. and everything works fine. except tracing. Just noticed that it happens not in the all projects. some are fine. Sending project by email now.
Erika Hello warmanw! It looks like in the project you sent us all the images had a 16 Bits/Channel mode setting. If you resave your images in 8 Bits/Channel instead of 16 auto-tracing should work again 😃