There have been cases in the past where the user ends up with a PDF Publish issue after signing the Document. We have restricted users to sign such files by giving the Protected Button. The protected Button would be disabled and the user can see the possible error by a mouse hover on the Protected Button and can refer to Item History for the possible error in the Revision File.
Here are some of the possible cases and how to fix such Document.
Fix Password Protected Files added in DMS Revision section
Fix Read Only Protected Files added in DMS Revision section
Fix Macro Enabled Protected Files added in DMS Revision section
Fix the missing images Protected Files added in DMS Revision section
Fix Image (having external links) Protected Files added in DMS Revision section
Fix the Custom XML Data Files added in DMS Revision section
Fix Corrupted or Unreadable Protected Files added in DMS Revision section (File Cannot be Added)