Regularly Back Up the Database

Oct 13, 2025 by pynkocean.com 97 views

**The Header for File 'xxx.mdf' is Not a Valid Database File Header: A Comprehensive Guide**

What is the Error Message?

The error message "Msg 5172, Level 16, State 15, Line 3" is a common issue encountered by SQL Server users. It indicates that the header for a specific database file is not valid, and the FILE SIZE property is incorrect.

Understanding the Error

When you detach a disk from a server, it can cause issues with the database files. The error message is usually triggered when SQL Server attempts to access the database file, but it finds an invalid header. This can be due to various reasons, including:

Disk Detachment: As mentioned earlier, detaching a disk from the server can cause issues with the database files.
File Corruption: Corruption in the database file can also lead to this error.
Incorrect File Size: If the FILE SIZE property is incorrect, it can cause SQL Server to fail when accessing the database file.

Q&A Session

Q: What are the possible causes of the error "Msg 5172, Level 16, State 15, Line 3"?

A: The possible causes of this error include disk detachment, file corruption, and incorrect file size.

Q: How can I resolve the issue of an invalid database file header?

A: To resolve this issue, you can try the following steps:

Check the Disk: Verify that the disk is properly attached to the server.
Run DBCC CHECKDB: Run the DBCC CHECKDB command to check for any corruption in the database file.
Rebuild the Index: Rebuild the index on the affected table to ensure that it is in a consistent state.
Restore from Backup: If none of the above steps work, you can try restoring the database from a backup.

Q: What is the FILE SIZE property, and how does it relate to the error?

A: The FILE SIZE property is a metadata attribute that stores the size of the database file. If this property is incorrect, it can cause SQL Server to fail when accessing the database file.

Q: How can I verify the FILE SIZE property of a database file?

A: You can verify the FILE SIZE property of a database file using the following T-SQL command:

SELECT FILEPROPERTY('E:\DATABASE\xxxx.mdf', 'Size') AS FileSize

Q: What are the consequences of ignoring this error?

A: Ignoring this error can lead to further issues with the database, including:

Data Loss: Corruption in the database file can result in data loss.
Performance Issues: An invalid database file header can cause performance issues with the database.
System Crashes: In severe cases, an invalid database file header can cause the system to crash.

Q: How can I prevent this error from occurring in the future?

A: To prevent this error from occurring in the future, you can:

Regularly Back Up the Database: Regular backups can help you recover from data loss in case of corruption.
Monitor Disk Health: Regularly monitor the health of the disk to ensure that it is properly attached to the server.
Run DBCC CHECKDB: Regularly run the DBCC CHECKDB command to check for any corruption in the database file.

Conclusion

The error "Msg 5172, Level 16, State 15, Line 3" is a common issue encountered by SQL Server users. It indicates that the header for a specific database file is not valid, and the FILE SIZE property is incorrect. By understanding the possible causes of this error and following the steps outlined in this article, you can resolve the issue and prevent it from occurring in the future.