PDF to PDF corruption
After Calibre added a particular PDF to the library (no conversion asked, just adding) the added PDF can't be opened in Acrobat Reader which complains the file is corrupt.
Acrobat Reader can open the original source PDF with no problem.
I conclude that Calibre does not simply copy the source PDF to its library (along with creating additional metadata) but rather does some kind of conversion (PDF to PDF).
This has happened to just a few of my PDFs. I can't figure out any special oddness in this specific PDF, other than it is rather large (45MB).
I am respectfully wondering... shouldn't Calibre just copy exactly from the source when adding to the library?