If you are encountering this error on a linux-based core (includes Synology, Qnap, Sonic Transporter) then the following workaround may get you going.
You need to re-start RoonServer twice in succession. Don’t reboot your core, just stop the Roon package and restart it (Synology, Qnap, Sonic Transporter). Wait until your remote reconnects and then stop and start again.
If you’re running a native linux install then stop and start Roon using systemctl.
Best to count to 10 between the stop and start just to give all of the processes a chance to exit cleanly.
And if you didn’t catch it above then I’ll reiterate. You need to stop and start Roon TWICE. No need to mess with the Tidal login or your cache directory.
Give it a shot… I’ll bet it works 