Trying to set up a product that was previously imported from Itch (On the Way to Chrysopoeia) and I get the above error after trying to save the draft or send it in for review. I have tried eliminating the uploaded PDFs and uploading them again as .zip, but no luck.
I just checked out the product, and I was able to save it with no issues. This could have been a temporary issue after you deleted a file, but the system cache thought it was still there.
If you’re still getting the error just let us know here and we’ll look into it further.