If your Veeam backups are failing with the following or similar errors:
Cannot create a shadow copy of the volumes containing writer's data.
A VSS critical writer has failed. Writer name: [SqlServerWriter]. Class ID: [{a65faa63-5ea8-4ebc-9dbd-a0c4db26912a}]. Instance ID: [{d0c7eea6-f80c-43e4-9625-8269bd1d675b}]. Writer's state: [VSS_WS_FAILED_AT_PREPARE_SNAPSHOT]. Error code: [0x800423f4].]
Unable to release guest. Error: Unfreeze error: [Backup job failed. Cannot create a shadow copy of the volumes containing writer's data. A VSS critical writer has failed. Writer name: [SqlServerWriter]. Class ID: [{a65faa63-5ea8-4ebc-9dbd-a0c4db26912a}]. Instance ID: [{d0c7eea6-f80c-43e4-9625-8269bd1d675b}]. Writer's state: [VSS_WS_FAILED_AT_PREPARE_SNAPSHOT]. Error code: [0x800423f4].]
Error: Unfreeze error: [Backup job failed. Cannot create a shadow copy of the volumes containing writer's data. A VSS critical writer has failed. Writer name: [SqlServerWriter]. Class ID: [{a65faa63-5ea8-4ebc-9dbd-a0c4db26912a}]. Instance ID: [{d0c7eea6-f80c-43e4-9625-8269bd1d675b}]. Writer's state: [VSS_WS_FAILED_AT_PREPARE_SNAPSHOT]. Error code: [0x800423f4].]
It lis likely that there is something messed up with the SQL Server. Even if you didn't install SQL, some programs use an instance of Microsoft SQL Express LocalDB. You will also see errors in the Application Event log such as:
Source: SQLVDI
Event ID: 1
SQLVDI: Loc=SignalAbort. Desc=Client initiates abort. ErrorCode=(0). Process=2404. Thread=380. Client. Instance=LOCALDB#SH3A9C8C. VD=Global\{D8287396-2820-4D92-B112-C1ABC614C622}1_SQLVDIMemoryName_0.
Source: VSS
Event ID: 8229
A VSS writer has rejected an event with error 0x800423f4, The writer experienced a non-transient error. If the backup process is retried,
the error is likely to reoccur.
. Changes that the writer made to the writer components while handling the event will not be available to the requester. Check the event log for related events from the application hosting the VSS writer.
Operation:
PrepareForSnapshot Event
Context:
Execution Context: Writer
Writer Class Id: {a65faa63-5ea8-4ebc-9dbd-a0c4db26912a}
Writer Name: SqlServerWriter
Writer Instance Name: SQL Server Code-Named 'Denali' CTP2:SQLWriter
Writer Instance ID: {d0c7eea6-f80c-43e4-9625-8269bd1d675b}
Command Line: "C:\Program Files\Microsoft SQL Server\90\Shared\sqlwriter.exe"
Process ID: 2404
Continue on for the simple solution...