Resolving SQL Server The Target Principal Name Is Incorrect Error Effectively

Have you recently encountered the SQL Server the target principal name is incorrect error? Looks confusing, right? This error might seem like a security or database corruption issue, when in reality it is an error related to a certificate or authentication mismatch. With the help of this write-up, we will try to get a clearer idea of this error and further understand how it can be resolved for better database accessibility and security. 

 

What is ‘The Target Principal Name Is Incorrect SQL Server Error’?

As we said earlier, this error might look like a security issue or corruption in the database, but there’s more to it. The SQL Server the target principal name is incorrect error mainly occurs when the SQL Server client, such as SSMS or any other application, fails to verify the identity of the server. This error generally pinpoints the issues with authentication, mismatched SSL/TLS certificates, or Kerberos Service Principal Names.

Let’s now take a clearer look at the reasons why this error occurs. 

Possible Causes for SQL Server The Target Principal Name Is Incorrect Error

Due to Failed Kerberos Authentication (Service Principal Names)

One of the common causes for this error to occur. When the database administrators try to connect to SQL Server using Windows Authentication, SQL Server depends on Service Principal Names for secure communication. In case the SPN for the SQL Server service is not properly registered, Kerberos will not be able to verify the connection. A few other reasons for authentication failure while making a connection are mismatched or duplicate SPNs. 

Mismatched SSL/TLS Certificate Names

This is another common cause that leads to a failed authentication issue, and further, the SQL Server the target principal name is incorrect error. When the SQL Server has a configuration to use encryption, the client validates whether the SSL/TLS certificates of the server match the specified hostname in the connection string. In case the certificate installed on the SQL Server does not have the same SANs or CNs (Subject Alternative Names or Common Names) as the ones configured with the server involved in making a connection, the authentication will fail.

Issues While Connecting Through Alias, IP, or Listener

After learning the two reasons, let’s now understand the third common reason for the occurrence of this error. In high-availability environments, when SQL Server tries to connect through IP, listener, or Always On Availability Groups, the error is often encountered. This might happen as for a successful authentication, the SPN and the certificates must include the listener name as part of the configuration. In case it doesn’t happen or the database administrators miss out this step, the SQL Server connection cannot be validated, further leading to the SQL Server the target principal name is incorrect error. 

We will now take a look at the ways that can help the users to resolve the error more effectively. 

Challenges Encountered By Users Due To The Error 

Here are some of the challenges the users encounter when this error occurs. We will understand these challenges one by one to find appropriate and effective solutions to resolve the issue.

• Risk of Connectivity Loss: When the error occurs, the applications and the database administrators cannot connect to the SQL Server.
• Database Inaccessibility Risks: As we read earlier, the SQL Server the target principal name is incorrect error might seem like a corruption issue, but it is an authentication error. However, with repeated failed authentications, the SQL Server database might become inaccessible. This can also lead to the SQL Server database marked as SUSPECT or RECOVERY PENDING mode. 
• Applications and Service Disruptions: With an inaccessible database, the applications and services relying on SQL Server might show failed login messages and errors.

Best Ways to Resolve the ‘SQL Server The Target Principal Name Is Incorrect’ Error 

After learning the causes for this error, it is now time to understand the ways and solutions for the the target principal name is incorrect SQL Server error. We will take a look at these methods one by one and try to learn their implementation to make the resolution process easier for the database administrators. Beginning with the first method, let’s see how it will help the users with error repair.

Method 1: Resolve the Error By Fixing Service Principal Names (SPN)

As we read earlier, one of the causes of the error is a mismatched or missing SPN during authentication. Therefore, to repair the error, we will first fix the SPN issue, which will help resolve the error effectively. Here are the steps for fixing SPN:

1. The first step is to find the SQL Server service account with the help of SQL Server Configuration Manager(SSCM). 
2. Next, go to SQL Server Services, and then go to Log On As option.
3. Then, using a domain controller or with the help of domain admin rights, list SPNs of the account. In CMD, the given command will help you with the same:
   

   setspn -L DOMAIN\SqlServiceAccount 

4. Next, it is crucial to check whether the required SPN exist or not to resolve the SQL Server the target principal name is incorrect error. The commands specified here will help:For default SQL Server Instance:

   MSSQLSvc/hostname.domain.local:1433
   
   MSSQLSvc/hostname.domain.local

   For custom SQL named instance

   MSSQLSvc/hostname.domain.local:PORT

5. In case the SPNs are missing, it is crucial to add them accordingly:
   

   setspn -S MSSQLSvc/sql01.domain.local:1433 DOMAIN\SqlServiceAccount
   setspn -S MSSQLSvc/sql01.domain.local DOMAIN\SqlServiceAccount

6. After this process is completed, it is required to purge Kerberos tickets and try again. Here is the command to help with the task:
   

   klist purge 

   (Purging here means to clear up the cache of Kerberos tickets)

This is how fixing of SPNs can be done, and further the SQL Server target principal name is incorrect can be resolved. Moving on to the next method, let’s see how it can help with resolving the SQL Server the target principal name is incorrect issue. 

Method 2: Repair SSL/TLS Certificate Issues to Fix the Error

Now, to fix the issues with the SSL/TLS certificates, we will understand the given steps:

1. In this method, we will use SQL Server Configuration Manager as well.
2. In SSCM, go to SQL Server Network Configuration, and then go to protocols. 
3. From protocols, move to the certificate tab.
4. Verify that the certificates meet the given conditions:
   1. They are present in the local computer.
   2. Has the Server Authentication.
   3. Has the server’s listener name or hostname in Common Name or Subject Alternative Name)
5. After verifying the following, update the connection string to match with the certificate name.
6. Once done, restart the SQL Server Service after assigning the authentic certificate.

This is how the certificate issues can be resolved; further fixing the target principal name is an incorrect SQL Server error caused due to the certificate issues. Moving on to the next method, let’s see how it will help.

Method 3: Fix SQL Server The Target Principal Name Is Incorrect In Always On and Clustered Environment

There is a possibility that the error might have occurred due to the Always On Availability Groups. Hence, the users must resolve the error accordingly. Here are the steps to resolve the error:

If the database administrators are using Always On Availability Groups, it is important to verify the following things:

1. The name of the listener has a valid SPN and is registered for the SQL Server Service Account. 
2. The certificates that are connected to SQL Server include the listener name in SANs.
3. The clients are connecting using the listener name. 

 Verifying these aspects can help the users fix the issues with server authentication. This will further resolve the error more securely. 

Conclusion

This write-up primarily focuses on the SQL Server the target principal name is incorrect issue. Here, we have discussed the major causes of the error and the challenges encountered due to the same error. Furthermore, we have explained the methods that will help the users to resolve the error in a precise way. So if you have encountered this authentication error, you can follow up with this guide and resolve the error.