I have been getting the same error as well. It just started happening about 6 weeks ago. Using version 18.104.22.168. On Windows 10 version 2004. See attached error message. Not showing any error in the log window.
The settings directory can't be written to, it's not a problem with RadioBOSS, it's either antivirus blocks the operation, or somehow access rights for the folder were modified. You can try reinstalling RadioBOSS to a different folder to see if it solves the issue.
Radioboss is installed in local C: Drive, there should not be any restrictions. Antivirus has been turn off. It has been working for over two years now nothing has changed except of OS patch updates. So my only guess is that that there may be conflict with this version of RadioBoss and OS I am running. Could there be a bug exposed in RB because of Windows updates?? I am no developer but research elsewhere suggest that there may be an issue around UTF 8 or UTF 16 encoding possibly in the scripts used by RadioBoss?