https://www.veeam.com/kb1785
KB1785: 0x8004230F or Error: VSSControl: -2147212529 (VSS_E_UNEXPECTED_PROVIDER_ERROR)
You receive errors "0x8004230F or Error: VSSControl: -2147212529" on Veeam Backup or Replication processes during VSS guest processing.
errorvssunexpectedprovider