Getting various errors when editing pdf's on a network drive with Adobe acrobat x ver 10.1.16

Hello, wondering if anyone can assist with an issue. About 10 users are getting various errors when editing pdf's on a network drive with Adobe acrobat
x version 10.1.16 and Xi version also.

• The pdf's are stored on a network drive that the
  users have been using for over 1 year without any issues.
• Users have read/write/edit access to this folder
• All users are assigned specific files to work
  and no one would be opening another users files.
  
  Some files could be worked for more than 8 hours per day but most are worked
  for less than 30 minutes at a time

Errors include:

1) The document could not be saved. The file may be read only, or another user
may have it open. Please save the document name or in a different folder.

2) The document could not be saved. Access Denied.

3) Bad File Handle when trying to save the pdf after editing

4) Acrobat has encountered an unknown error