InDesign is shooting Error Code 14

Hi!
We work as a team on several InDesign documents on Mac. Some of us are updated to OS Sierra since the weekend some still use OS X El Capitan.
Since Monday InDesign just refuses to open documents and shoots error code 14 "file was incompatible with Adobe InDesign (Error Code 14)" the documents are stored on our intern server. A restart of that didn't help.
Not everyone in the office has that problem and just random documents can't be opened and sometimes the Error "page is still opened by some other user" appears, even if thats not the case.
We thought our antivirus program (Sophos) could be the issue and deinstalling would help, but it didn't...
Our normal workflow became a big fuss. Does anyone have any hints for another workaround of that problem?
Thanks!


