Repair operation can be used in the following scenarios:
Repair an instance of SQL Server that is corrupted after it was successfully installed.
Repair an instance of SQL Server if the upgrade operation is cancelled or fails after the instance name is mapped to the newly-upgraded instance.
If you see the following message in the summary log, you can repair the failed upgrade instance:
"SQL Server upgrade failed. To continue, investigate the reason for the failure, correct the problem, and then repair your installation."
If you see the following message in the summary log, you need to uninstall and reinstall SQL Server. You cannot repair the SQL Server instance.
"SQL Server upgrade failed. To continue, investigate the reason for the failure, correct the problem."
When you repair an instance of SQL Server:
All missing or corrupt files are replaced.
All missing or corrupt registry keys are replaced.
All missing or invalid configuration values are set to default values.
Before you continue, for SQL Server failover clusters, review the following important information:
Repair must be run on individual cluster nodes.
To repair a failover cluster node after a failed Prepare operation, use Remove node and then perform the Prepare step again. For more information, see Add or Remove Nodes in a SQL Server Failover Cluster (Setup).
To repair a failed installation of SQL Server from the Installation Center
Launch the SQL Server Setup program (setup.exe) from SQL Server installation media.
After prerequisites and system verification, the Setup program will display the SQL Server Installation Center page.
Click Maintenance in the left-hand navigation area, and then click Repair to start the repair operation.
If the Installation Center was launched using the start menu, you will need to provide the location of the installation media at this time.
Setup support rule and file routines will run to ensure that your system has prerequisites installed and that the computer passes Setup validation rules. Click OK or Install to continue.
On the Select Instance page, select the instance to repair, and then click Next to continue.
The repair rules will run to validate the operation. To continue, click Next.
The Ready to Repair page indicates that the operation is ready to proceed. To continue, click Repair.
The Repair Progress page shows the status of the repair operation. The Complete page indicates that the operation is finished.
To repair a failed installation of SQL Server using Command Prompt
Run the following command at a command prompt:
Setup.exe /q /ACTION=Repair /INSTANCENAME=instancename