SCCM site back-up is one of the essential back op options. Even your environment is stable, you may receive alerts in smsbkup.log as below:

Cannot find the dependent writer. The dependant component cannot be backed up.AddDependentComponent(pDependency) failed. Error code = 0x80,004,005.Error description = .Error: GatherWriterMetadata failed.

This error indicates that either SMS_SITE_VSS_WRITER or SQL Server VSS Writer is not listed as one of VSS.

In order to eliminate this error,

1. Start CMD with admin privilege.
2. Enter the command VSSAdmin list writers
3. Review the list for the missing writer.
4. Restart the missing writer service from services.msc
5. Start the SMS_SITE_BACKUP service.
6. Monitor smsbkup.log for any issues. Ensure that the back-up is completed.