Error with update device full cache clear error

[nepti]

@shelled

Disk is not full

Yes, it is.

@shelled

ID-1: / raw-size: 71.28 GiB size: 71.28 GiB (100.00%)
used: 69.64 GiB (97.7%) fs: btrfs dev: /dev/dm-0 maj-min: 254:0
mapped: luks-55e381a9-1da2-4774-9917-9126737d9ffd
ID-2: /boot/efi raw-size: 100 MiB size: 96 MiB (96.00%)
used: 31.3 MiB (32.7%) fs: vfat dev: /dev/nvme0n1p1 maj-min: 259:1
ID-3: /home raw-size: 71.28 GiB size: 71.28 GiB (100.00%)
used: 69.64 GiB (97.7%) fs: btrfs dev: /dev/dm-0 maj-min: 254:0
mapped: luks-55e381a9-1da2-4774-9917-9126737d9ffd
ID-4: /var/log raw-size: 71.28 GiB size: 71.28 GiB (100.00%)
used: 69.64 GiB (97.7%) fs: btrfs dev: /dev/dm-0 maj-min: 254:0
mapped: luks-55e381a9-1da2-4774-9917-9126737d9ffd
ID-5: /var/tmp raw-size: 71.28 GiB size: 71.28 GiB (100.00%)
used: 69.64 GiB (97.7%) fs: btrfs dev: /dev/dm-0 maj-min: 254:0

Root is full…once again.

@shelled

deleted 500 mb to test went down to 5 mb from 66 after that.

That’s not enough, you need more free space. Obviously you don’t understand how BTRFS works and that automatic snapshots are created before and after a system update. And if you run out of space during or after a successful update, you will no longer be able to boot.
In addition to @Duke187’s suggestion, you should also delete old snaphots.