I have encountered instances of individual PDF files (booklets) which fail to upload to MB.  I get the error "Error Uploading Image".  At first I thought it was because the file was too big and just ignored those booklets.  After a while I noticed that much bigger PDF files were uploading successfully.  I just found another booklet which refuses to upload.  I have made repeated failed attempts to upload it, even over several days, so I think it is not an intermittent error but something specific to the file.

I have attached the troublesome file.  I have been trying to add it as "booklet" to here:

https://musicbrainz.org/release/b2852330-375b-4d78-a8df-222a0497afd8/add-cover-art