BA6111: An input/output error occurred while accessing the device¶
| Error code | Product | Applies to |
|---|---|---|
| BA6111 | BackupAssist | For BackupAssist 14.0.0 or later. |
Description¶
The System Protection (New Engine) backup reports BA6111 when a low-level input/output error occurs while reading from or writing to the backup destination device. It almost always means the destination device is failing or was intermittently unavailable during the backup, or that the backup's VHDX chain on the destination has been damaged.
Common causes:
- Bad sectors or a failing destination drive.
- A loose or faulty USB / eSATA cable or port, or the drive briefly losing power.
- A NAS or network destination dropping out during the backup.
- A corrupted VHDX in the incremental backup chain.
Resolution¶
Resolution 1 - Check and repair the destination device (recommended)¶
- Open Windows Event Viewer and check the System log for disk errors (source: disk) around the backup time.
- Run "chkdsk /f /r" on the destination volume from an elevated command prompt.
- For an external drive, try a different cable and port and connect it directly rather than through a hub; for a NAS/network destination, check its stability and power management.
Note: "chkdsk /f" needs exclusive access to the volume and dismounts it while it runs. On a volume that is in use it cannot run until the next restart, when Windows schedules the check and prompts for a reboot. Run it outside backup and production hours.
Resolution 2 - Restart the backup chain¶
Because the existing VHDX chain on the destination may be damaged, create a new backup job (or force a new full backup) so a fresh chain is started. A new job often succeeds because it writes to different, undamaged storage.
Resolution 3 - Replace failing hardware¶
If chkdsk or the event log shows the drive is failing, replace it. A full format onto known-good media, or a new drive, resolves recurring BA6111.
Note on the backup report¶
The backup report shows: An input / output error occurred while accessing the device
| Last updated | Created | Further assistance |
|---|---|---|
| 15th Sep 2026 | 18th Oct 2023 | BackupAssist Support page |