ERROR CODE [23:90] Failed to open or read at least one item.

Synthetic Full reports failure to read item(s).

Symptoms

Usually seen in conjunction with error code 13:138:

Error Code: [13:138] Description: Error occurred while processing chunk [########] in media [V_########], at the time of error in library [Name] and mount path [[MediaAgent] Path], for storage policy [Name] copy [Name] MediaAgent [Name]: Backup Job [ID#]. Operating System could not find the device file specified. The device may be unreachable from the MediaAgent.

Error Code: [23:90] Description: Failed to open or read at least one item. Source: MediaAgent, Process: SynthFull

Causes

• Mount path is inaccessible (offline, running other processes) or corrupt
• Index is corrupt
• Missing incremental backups

Resolution

Verify mount paths are accessible and available. Retry Synthetic Full job.  If the error reoccurs, run a true full backup.