World SDK upload error 'Invalid file extension'

Hi! I’m trying to upload my first world, but the SDK is having an issue and I can’t seem to figure it out.
error1


The “asset bundle” error is the one it throws immediately after it begins uploading. After that, it seems to upload smoothly until finishing, and then tells me the upload failed with “Invalid file extension”. The error details contain lots of references to the thumbnail image, so it could have something to do with that? Has anyone else experienced this error?
I’m on Linux, using the Flatpak version of Unity with the current Unity editor and the current SDK, and I’ve never had any problems uploading avatars.

The info message with the status code of 400 seems like a bigger problem especially as it’s first shown.

The complaint for file extension looks like it’s directly after a failed upload





Here are the details for some of the errors thrown. (400, AssetBundle, 404, Invalid file extension)

Nothing above it declaring that the AssetBundle was not built? that is a critical step in making an avatar, and so if the SDK is trying to still upload something while it doesn’t actually have a build, I wouldn’t bother reading anything the SDK says after that, unless I’m working for VRChat looking for some bugs to fix

I was hopeful the most recent SDK update would patch whatever is going on, but it’s still happening. So, if the world isn’t being built, then what could be preventing it?
The console doesn’t seem to provide much info to go on. Is there another type of logging I could try to track down the issue?