When backup tools such as Azure Recovery Vault perform a backup on a virtual machine (VM), they might fail to achieve application consistency. There might not be any errors. The application runs fast without any backups being done. The SQL Server Volume Shadow Copy Service (VSS) Writer ends up in a non-retryable error state. If you enable SQL Server VSS Writer trace, you might see the following exception, which indicates there's no database to freeze, resulting in an unsuccessful snapshot:
[0543739500,0x002948:011b4:0xb87fa68e] sqlwriter.yukon\sqllib\snapsql.cpp(1058): Snapshot::Prepare: Server PROD-SQL01 has no databases to freezeAdditionally, some databases might be detected with Online:0:
[0543739390,0x002948:0x11b4:0xb87fa68e] sqlwriter.yukon\sqllib\snapsql.cpp(0408): FrozenServer::FindDatabases2000: Examining database Online:0 Standby:0 AutoClose:0 Closed:0If you use Azure Recovery Vault, you might see an error like the following one in the event list:
App-consistent recovery point generation failed.The issue arises from a code change in SQL Server 2019 CU28 that checks if a database is online and ready to be frozen. The current solution is to roll back to SQL Server 2019 CU27 and perform the snapshot backup. For more information about how to roll back the package to a previous version, see Uninstall a Cumulative Update from SQL Server.
Microsoft is working on a fix for this issue and it will be available in a future CU.