- Edited
After failing in the usual way to update my four Solus VMs over the weekend, I found some time to try again yesterday. Budgie and Plasma both failed again, but with a different error than before: the Linux firmware completed with just one timeout, but the resulting package did not match what was in the repository.
I was encouraged by GNOME and Xfce both updating without any drama, and at normal speeds. Afterwards, I tried the Budgie update again, and this time it also completed normally and at the usual download speed. Same with Plasma. So, apparently it depends on when an update is started whether it will succeed.
NOTE: I didn't use Harvey's workaround for these VMs, because they didn't need to be updated right away, and I was particularly interested in whether - and when - the situation would be resolved and normal updates once again became possible. That appears to be a work in progress.
ALSO NOTED: This morning I updated my Xfce laptop as well, and that proceeded without a problem. At a normal speed - which is very fast for Xfce - and no errors of timeouts. Again, this was without a workaround of any kind.