Problem Description:
A full Microsoft SQL backup job may fail with Phoenix Error Code 54 when one or more databases included in the backup set are in read-only mode.
This happens because the SQL VSS Writer cannot perform a standard full backup on read-only databases, leading to job failure.
Symptoms:
Backup job fails with error Phoenix 54.
Failure is limited to databases that are configured as read-only.
Windows Event Viewer logs contain entries similar to:
A VSS writer has rejected an event with error 0x800423F4.
Writer Name: SqlServerWriter
Writer Instance Name: Microsoft SQL Server 2017:SQLWriter
SQLSTATE: 25000, Native Error: 3906
Error message: Failed to update database "ABC" because the database is read-only.
Cause:
The Microsoft SQL Server VSS Writer (SqlServerWriter) requires write access during a full backup operation.
If a database is in read-only mode, the writer cannot update metadata or perform a checkpoint, resulting in a backup failure with Phoenix 54.
Resolution:
Option 1: Enable Backups by Switching the Database to Read/Write Mode
If backups are required for the affected database:
Connect to SQL Server Management Studio (SSMS).
Run the following command to change the database to read/write mode:
ALTER DATABASE ABC SET READ_WRITE;GORetry the backup job.
(Optional) Revert the database to read-only mode after successful backup:
ALTER DATABASE ABC SET READ_ONLY;
GO
Option 2: Keep Database Read-Only and Perform Copy-Only Backups
If the database must remain read-only:
Exclude the read-only database from the Druva Phoenix backup set to prevent backup job failure.
Go to Druva Console → Configurations → Backup Sets → Edit and deselect the read-only database.
Configure a manual Copy-Only Backup using SQL Server:
BACKUP DATABASE ABCTO DISK = 'D:\Backups\ABC_CopyOnly.bak'WITH COPY_ONLY;GOThis approach ensures that backups are still taken without altering the database’s state.
Option 3: Backup Remaining Databases
If other databases exist in the same backup set, the read-only database can be temporarily excluded to allow the remaining databases to back up successfully.
Verification:
After applying the above steps:
Verify that the next backup job completes successfully in the Druva Console.
Confirm that no new VSS Writer or SqlServerWriter errors appear in the Windows Event Viewer → Application Logs.
Ensure the generated backup file (.bak) is valid and restorable.
Additional Information:
Standard SQL full backups require databases to be in read/write mode.
Read-only databases cannot participate in standard full backups through VSS; use Copy-Only backups or transaction log backups instead.
This issue is environment-specific and does not indicate data corruption or a malfunction in Druva services.