What kind of hopefully graceful failure will occur if there is not enough free disk space? Someone is bound to exercise that path!
For those who don’t have enough free disk space, will it work to take a backup, and then restore into a fresh install, as a migration?
(In which case, it might also be a good time to move up to a new LTS version of the operating system. Ubuntu 26.04 is pretty new; 26.04.1 is expected very shortly. A fresh OS install may be less troublesome than an attempted upgrade in place.)