Backup failures

Backup alerts firing — what they mean and how to fix.

There are two distinct backup alerts:

Different causes, different fixes.

"Backup Failed"

3CX itself reported the backup attempt failed. Common causes:

If your 3CX is backing up to local disk and the disk filled up.

Fix: 3CX admin → Backup → check destination disk usage. Either free space or re-point to a larger volume.

If your backup target is an SMB share, S3 bucket, FTP, or Google Drive that became unreachable.

Fix: Test reachability from the 3CX host. Re-authenticate cloud storage (Google Drive tokens expire). Re-test the backup.

The credentials for the backup destination changed or expired.

Fix: Update credentials in 3CX admin → Backup → [Destination].

Some destinations have file-size limits. A 3CX with thousands of extensions can produce a backup > 2 GB; some FTP servers reject.

Fix: Move to a destination without the limit (cloud storage, big SMB share).

Backups aren't even attempting, or have been failing for 7+ days without anyone noticing.

3CX → Backup → Schedule. Make sure the backup schedule is enabled and that the cron / interval is sane.

If the 3CX service is in a degraded state, scheduled tasks may not fire. Check the instance's Services tab.

A schedule "every day at 02:00" needs the host's clock to be roughly correct. If the 3CX host's time drifted, the schedule may have skipped runs.

Fix: Sync the host clock (NTP). Restart the 3CX service.

Health-score bands (after May 2026 relaxation):

Backup Stale alert fires at the > 168 h boundary.

If you know backups will fail (planned destination migration, etc.), add a maintenance window on the instance to suppress alerts during the work.

Per-instance detail → Backups tab shows every attempt with:

Useful for spotting "it worked yesterday, then started failing" type patterns.