Quite a bit of things went wrong - but most of them I was able to revert.
This one however, slaps me in the face and I can't see what the issue is.
> xc: panic: xc_dom_core.c:387: xc_dom_do_gunzip: inflate failed (rc=-5): Internal error
> xc: panic: xc_dom_bzimageloader.c:713: xc_dom_probe_bzimage_kernel: unable to gzip decompress kernel: Invalid kernel
A bit of googling revealed that either the initramfs image is corrupt.
Or there is not enough space.
I verified that both of them are not the case:
> cd /var/lib/qubes/vm-kernels/KERNELVERSION/
> gzip -t initramfs
> df -h
Shows no use above 18%. The combined use of them all is < 30%.
The root dir "/" has a use% of 10%.
> sudo vgs
qubes_dom0 has a VFree of 15.91g