Updating Fedora with Read-Only Root Filesystem
dnf system-update on a Fedora machine that has a read-only root
filesystem, it is important to make sure that the filesystem will be mounted
read-write automatically first. Edit
/etc/fstab and change it to
before rebooting, lest the update will fail.
I imagine the offline update process really should remount the root filesystem on its own, but that does not appear the case, at least for now.