Timeshift pre-update snapshot abort when the system partition lacks free space in Linux Mint Update Manager

Linux Mint's Update Manager can invoke Timeshift before applying updates, but snapshot creation aborts when the root partition lacks free space or the filesystem is unsupported. On ext4, snapshots rely on rsync and hard links, which consume more time and space than BTRFS subvolume copies and are more likely to hit capacity limits. Timeshift defaults to excluding /home, so a system restore reverts applications and settings but leaves user data untouched; however, changing that exclusion increases snapshot size and may worsen the space pressure that causes the abort.

The unresolved decision is whether to retain the default /home exclusion and accept that user data requires separate backup tooling, or to include /home in snapshots despite larger, slower backups that are more likely to trigger the insufficient-space failure. Retention policy configuration also affects whether automatic snapshots accumulate and eventually fill the partition over time. Behavior varies by Linux Mint version and Timeshift release, so defaults should be verified on the installed system rather than assumed.

Should the default /home exclusion be preserved to minimize snapshot footprint, or does including user data in system snapshots provide a safer rollback path despite the increased risk of pre-update snapshot aborts? What retention thresholds prevent automatic snapshots from exhausting the root partition and reintroducing the failure? What is the correct recovery procedure when an interrupted Timeshift snapshot is retained and blocks subsequent snapshot attempts during Update Manager runs?