Subtitle Backups

Every time you press Save in the Subtitle Editor, Sublarr renames the previous version of the file to <name>.<ext>.bak before writing the new content. The .bak files accumulate next to the originals and are pruned by the cleanup scheduler after the configured retention. The Subtitle Backups page is where you list, preview, and restore them.

Why backups exist

Subtitle edits are easy to get wrong — a misplaced timing nudge or a bad bulk replace can render half a season unwatchable. The .bak file is a no-cost insurance policy: the previous good version is always one click away, no version control, no manual copy-and-paste.

The page layout

Open it from Settings → Cleanup → Subtitle Backups or directly at /settings/cleanup/subtitle-backups. The view is a flat list of every .bak file Sublarr knows about, grouped by source media file.

Column	Effect
Media	The video the backup belongs to.
Original sidecar	Path of the live subtitle the backup would replace.
Backup created	Timestamp of the save that produced this .bak.
Size	Bytes of the backup.
Expires	Days until the cleanup scheduler removes it.
Actions	Preview · Restore · Delete now.

Preview before restore

The Preview action opens a side-by-side diff modal: the live subtitle on the left, the backup on the right, with cue-by-cue alignment. Color highlights mark added/removed/edited cues so you can confirm you really want to roll back before committing.

Indicator	Meaning
Green block	Cue exists only in the backup — restoring brings it back.
Red block	Cue exists only in the current — restoring removes it.
Yellow text	Cue exists in both but with different text or timing.

Restore behaviour

Clicking Restore:

1. Renames the live sidecar to <name>.<ext>.<timestamp>.bak.bak (rolling pre-restore safety copy).
2. Renames the chosen backup back to the live filename.
3. Triggers a cache invalidation so the Library and Editor pick up the restored content immediately.

Tip

The “rolling pre-restore safety copy” means restoring a backup creates another backup. So even a wrong restore is reversible — find the freshly-created .bak.bak in the list and restore that.

Retention

.bak files are kept for the period set in Settings → Subtitles → Stream Management → Subtitle backup retention (default 14 days). The scheduler runs the prune nightly. Files older than the retention are deleted; the live sidecar is never touched.

Retention	When it makes sense
7 days	Tight disk budget; you mostly catch mistakes the same day.
14 days (default)	Sane for most installs.
30 days	Liberal — gives you a full month to notice a regression in production.
0 / disabled	Backups still get written but never pruned. Use only with explicit disk monitoring.

How .bak is different from Trash

Both are recovery surfaces, but they serve different actions:

Action	Recovery via
Editor save	.bak sidecar (this page).
Cleanup → orphan delete	Trash.
Stream Management → foreign-track removal	Trash (MKV backups).
Cleanup → format upgrade	Trash (sidecar batch).

Batch operations

When you have a clear “this whole folder needs to roll back” situation, use the row-multi-select checkboxes plus Restore selected in the toolbar. The pre-restore safety copies still get created — even bulk restores stay reversible.

Caution

Bulk restore reads from disk for every file in the batch. On NFS or slow storage this can take noticeable time. The job runs in Activity → Queue so you can navigate away while it works.

When .bak is missing

If you can’t find the backup you expected:

Reason	Where to check
Retention window passed	Adjust Subtitle backup retention so future backups stick around longer.
Filesystem read-only at save time	Logs — look for bak_write_failed warnings around the save.
Backup deleted manually	Check Activity → History for bak_deleted entries.
Editor save failed silently	The pre-edit content was lost; recover from your media-library backup if you have one.