I use ASTAP for NINA continually, and now use it for APPM (with NINA as a camera). I have never had it give an error. I have had it fail occasionally to find a solution, especially if you give it bad image scale, but never had it throw an error like that. And I know a lot of other NINA users with similar experience.
That’s not to say it doesn’t, I do not doubt the reports… I am just curious what’s different about how people are using it through APPM?
Are those for whom it is failing using APPM to control the camera (as opposed to another software like TSX or NINA to control the camera)? Could it be something about the FITS headers that variers depending on the capture program?
But from what I recall the list of other solvers includes some hefty associated software, e.g. to use imagelink from Bisque you need TSX, which is a pretty massive set of software for just a solver. ASTAP is the lean version.