Having reverted to KStars 3.3.6 on Windows I can now run the polar alignment tool successfully for the first time. It was crashing the whole application on attempting to solve the error after taking the 3rd image on KStars 3.3.8 on Windows 10, and also on KStars 3.3.7 running on the Raspberry Pi 4.
I have managed to work around my solver issues by installing ansvr on Windows now and pointing the online solver at localhost:8080 where I am running this service. So at least I can now do quick offline solves on the Windows laptop now.
Just to confirm I am seeing the same symptoms. After struggling for some time to configure remote astrometry.net solving I googled the error message text and found this thread. I am running KStars on Windows 10 with my remote indi server being a Raspberry Pi 4 using the astroberry 2.0.0 distribution.
With KStars 3.3.8 I get the error on connecting to the remote INDI server that the astrometry.net binaraies cannot be found.
I downloaded the latest nightly to test (build 220) but this crashes as soon as I start EKOS, or sometimes when I first click on the align tool tab.
I also tried build 218 and see the same crash.
Now reverted to KStars 3.3.6 and it appears to connect OK now, but the solver always fails. I tried to turn on debug via the INDI control panel, but it immediately turns itself off again. Not sure where to go from here.