Transient and Non-transient errors when using guest processing

0x800423F3 translates to the VSS error “VSS_E_WRITERERROR_RETRYABLE” or “The writer experienced a transient error. If the backup process is retried, the error might not reoccur.”
 
This error is expressing that a generic error has occurred and that the backup may be retried and may be successful on the next attempt. In order to investigate the core issue, refer to the System and Application event logs from the guest at the time of error.

0x800423F4 translates to the VSS error “VSS_E_WRITERERROR_NONRETRYABLE” or “The writer experienced a non-transient error. If the backup process is retried, the error is likely to reoccur.”

This error is expressing that a generic error occurred in the backup process and is likely to happen again. This error is typically due to system configuration or other software that prevents the execution of a shadow copy. In order to investigate the core issue, refer to the System and Application event logs from the guest at the time of error.

Both of these errors may be indicative of another error occurring within guest processing. In Hyper-V backups, this may occur on the host or storage snapshots themselves.  In many cases, you can verify if this is an inherent system or configuration issue by executing a native Windows Backup on the guest, or in the case of Hyper-V backup configured for OnHost, a native VM backup.

For assistance with investigation of the core issue or verifying information posed in any event logging, please open a Veeam Support case.