A few months back, WSJT-X stopped controlling my Kenwood TS-450. I didn't have time or patience to trouble shoot at that time. Now I'm ready to dive into it.
First, I believe this is a problem with the Kenwood library, because the program continues to work fine with my Yaesu FT-817. Also the error message indicates this. Another program (Mixw-4) using the same com ports is able to control the Kenwood fine.
The big mystery is why, when it once worked fine with the Kenwood, it stopped working suddenly.
What I have tried:
Re-installing (more than once)
Trying different com ports (because I had an issue with enumeration of the sound card once before)
Clearing and re configuring the settings.
Refreshing windows 10 with a repair upgrade.
None of this worked. I could use a hint from someone who really understands how the rig library works and how one can fix or update it.