[Export keeps giving me 'error' messages]

I'm trying to export my files (kids books) but I can't seem to export anything anymore to pdf.

Even the files that were previously exported with no problem, give me an error message now.

I've tried to make the placed files (images) smaller, but it keeps happening.

Also, I've tried exporting the document to several different pdf export options... still error.

Maybe an upgrade that I missed?

Please help!