Working with PDF file we can get this error : “The document could not be saved. The file may be read-only, or another user may have it open. Please save the document with a different name or in a different folder”
While this error we can not save pdf file after editing. So reason of this preview pane of Windows which a preview PDF file is being displayed and because of that Windows Explorer reads the file and keeps it open. Solve this we just need turn off Preview pane in the Windows dialog.