Can not upload to steam workshop

[Deleted member 58016]

just to be sure, what's the size of your preview image ?
pretty sure it has to be less than 1 meg.
I had issues before where i didn't receive any meaningful error, pretty sure it was the same build config file error, but it was down to the preview image being too large.

oh and thanks for the link to the tool, never seen that before

This should give an error message - and I think it does but an undefined / misleading one - but maybe it is the cause and the error message is not seen or is not appearing for some reason (but at least I think he should return to prompt after a couple of seconds).