{single}{actor}{/single}{multiple}{actors}{/multiple} replied to the...

Here are some more details from stderr:

1. Canon driver configured with FITS transfer. Probably not an issue for regular light/dark capture, since native works fine, but this is a clue about what might be going wrong with StellarSolver capture- exactly the same error message appears (with a different tmp file).

org.kde.kstars.indi: Canon DSLR EOS M50 :  "[INFO] Starting 1 seconds exposure. "
org.kde.kstars.indi: Canon DSLR EOS M50 :  "[ERROR] Cannot open /tmp/indi_2DMHET: Unsupported file format or not RAW file "
org.kde.kstars.indi: Canon DSLR EOS M50 :  "[ERROR] Exposure failed to parse raw image. "

Switching to my ZWO guide camera and attempting to plate solve, I see dozens of failed mmap messages like this:

org.kde.kstars.ekos.align: "Capturing image..."
Found one coordinate representation.
org.kde.kstars.ekos.align: "Image received."
system: Cannot allocate memory
/home/astroberry/Projects/stellarsolver/stellarsolver/astrometry/util/fitsbin.c:541:read_chunk: Couldn't mmap file "/home/astroberry/.local/share/kstars/astrometry/index-4204-04.fits"
system: Cannot allocate memory
/home/astroberry/Projects/stellarsolver/stellarsolver/astrometry/util/fitsbin.c:541:read_chunk: Couldn't mmap file "/home/astroberry/.local/share/kstars/astrometry/index-4204-03.fits"
system: Cannot allocate memory
/home/astroberry/Projects/stellarsolver/stellarsolver/astrometry/util/fitsbin.c:541:read_chunk: Couldn't mmap file "/home/astroberry/.local/share/kstars/astrometry/index-4204-03.fits"
/home/astroberry/Projects/stellarsolver/stellarsolver/astrometry/util/quadfile.c:135:my_open: Failed to open quads file
/home/astroberry/Projects/stellarsolver/stellarsolver/astrometry/util/index.c:417:index_reload: Failed to read quads from /home/astroberry/.local/share/kstars/astrometry/index-4204-03.fits
/home/astroberry/Projects/stellarsolver/stellarsolver/astrometry/blind/engine.c:204:engine_add_index: Failed to load index from path /home/astroberry/.local/share/kstars/astrometry/index-4204-03.fits
system: Cannot allocate memory