Something went wrong: there was an error publishing your course - How to resolve

This was taken from a historic post similar to our problem - maybe it's helpful for some of you?

"We have an issue with exporting courses that contain an asset with the % symbol in the file name. That could include an image, a PDF, or another piece of media. We're working on a fix, and I'll let you know when it's out!"

I won't be making any wholesale changes to my content at the minute.  I'm gonna ride this one out and trust the techies to come up with a fix...