The SQL error 5120 is a common error that is triggered when the account that runs the SQL service does not have the permission to use MDF files of a database.

As a part of our Server Management Services, we help our customers to fix MS SQL errors such as this one regularly.

Let’s today discuss the possible causes and fixes for this error.

What causes SQL error 5120?

SQL error 5120 triggers while attaching databases. It happens due to a number of reasons. A typical error message looks like:

The possible reasons for this error include:

1. Storage of MDF files in an inaccurate location: The main reason for error 5120 is the storage of MDF database files in an inaccurate location. It means that the MDF file is stored in some other drive of a computer.

2. Insufficient permission for system drives to store server file: System drives might not be having permission to store the server file within them. Thus, when a user tries to connect database files to the server, it results in the occurrence of SQL server 5120 messages.

Apart from these common reasons, some alternate reasons like not opening SQL Server Management Studio with admin right, not using Windows Authentication account, etc.

Let us now look at the possible solutions to fix this error.

How to fix SQL error 5120?

As we discussed earlier,  the primary reason for this error message is insufficient permission to attach or detach the database. Thus the method to fix it include changing the permission of the file or moving the files to another directory.

Add permission to the drive

To add the required permission to the file, we need to

1. First right-click on the MDF or LDF file and click on properties.

2. From the Security tab, click on the user.

3. Now change the permission to full control and click on OK.

This will fix the issue.

At times, granting full permission may not fix the error 5120. Major problems within your SQL database can trigger this error. In that condition, either restore entire data from SQL Backup or a repair of the corrupted SQL Database will be required.

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Conclusion

In short, the error 5120 triggers due to the absence of permissions or due to a wrong storage location of database log files. Today, we discussed how our Support Engineers fixes this error.