Many thanks Arnd for your detective work! Fantastic!, and thanks to Irad for hopefully fixing it. I have sent an email to request the test version. Dave M0WID

Still having issues. I understand how tricky it is to deal with so many users, and I will be away for a few days so no rush. If you need any more info or wish me to test anything then just ask or send a mail. Here is an example from SparkSDR log when it is communicating with WSJT-X using rigCtld 14/05/2024 20:00:00 v2.0.974.0 899701 rigctl ->F 14079000.000000 14/05/2024 20:00:00 v2.0.974.0 899702 rigctl <-RPRT 0 14/05/2024 20:00:00 v2.0.974.0 899703 rigctl ->v 14/05/2024 20:00:00 v2.0.974.0 899704 rigctl <-VFOA 14/05/2024 20:00:00 v2.0.974.0 899705 rigctl ->T 1 14/05/2024 20:00:00 v2.0.974.0 899706 rigctl <-RPRT 0 14/05/2024 20:00:00 v2.0.974.0 900028 rigctl ->s 14/05/2024 20:00:00 v2.0.974.0 900032 rigctl <-0 VFOA 14/05/2024 20:00:00 v2.0.974.0 900034 rigctl ->m 14/05/2024 20:00:00 v2.0.974.0 900043 rigctl <-PKTUSB 3430 Many thanks Dave M0WID

And another log file starting from a fresh .ini file, debug on, changing the frequency drop down. Hope it helps. Thanks again, Dave M0WID

Thanks for the reply log and .ini file attached as a zip. Screenshot of the exception: