The error message you’re seeing indicates a problem with the SSL/TLS certificate used by the SQL Server. This typically happens when the server uses a self-signed certificate or a certificate issued by a Certification Authority (CA) that is not recognized by the client system. To resolve this issue, you have a few options:

1. Install the Certificate as a Trusted Root on the Client: Import the certificate used by the SQL Server into the trusted root certificates store on the client machine. This tells the client system to trust the certificate, and it should no longer raise an error when connecting.
2. Update the Connection String: If you are using a connection string to connect to SQL Server, you can add TrustServerCertificate=True; to the connection string. This bypasses the validation of the server certificate. However, be aware that this reduces security by making your connection susceptible to “man-in-the-middle” attacks, so it’s not recommended for production environments.
3. Update the SQL Server to Use a Certificate from a Trusted CA: Obtain and install a certificate issued by a CA that is trusted by the client systems. This is the most secure approach, as it ensures that the identity of the SQL Server can be verified by the clients without needing to bypass security checks.
4. Ensure Correct Configuration on SQL Server: Make sure the SQL Server is correctly configured to use the certificate. This includes setting the correct certificate in the SQL Server configuration manager and ensuring the SQL Server has access to the certificate’s private key.
5. Check for Certificate Revocation: Ensure the certificate has not been revoked. A certificate revocation list (CRL) check failure can also cause this error if the client system cannot reach the CRL distribution points to verify the certificate’s revocation status.
6. Update Client and Server to Trust the CA: If the CA is not globally recognized but is an internal or private CA, ensure both the client and server systems have been configured to trust certificates issued by this CA.

If you’re not sure how to proceed with these options, you might want to consult with your IT department or a network security professional to find the best approach for your specific environment.