If you get this error message then SimpleumSafe can not access (write) a safe’s database.
The error message also displays the file name. Please check if you have read and write permissions on the specified file.
In the Finder, go to the safe file (with file extension .Safe). Select “Show package contents” in the context menu. Now you see all the files that belong to a safe. Go to the file specified in the error message and look at the file information (context menu> Information> Access Rights)