When saving a document stored on a network drive, this error occurs when clicking save.
If the document is copied locally the error does not occur.
NTFS Permissions are all correct.
This issue arrose for me and the issue was that “Offline Files” was causing an issue. When I opened and cleared the temporary offiline files from the Sync Center this solved the problem. Also when I re-enabled the offline files for this document the issue returned.