On Ubuntu 24.10+ /tmp is a size-limited tmpfs, so mktemp -d staging could not hold the uncompressed copy of the panel, web roots and certs. Stage backup/restore work dirs inside /var/backups/x-ui instead, and verify free space (2x estimated size + 100 MB margin) before touching anything. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>