Error: Named Instances Can Only Be Used With Direct or Private Link Connection Methods

Issue

The following error appears:

Invalid Form Input Detected: Named Instances Can Only Be Used With Direct or Private Link Connection Methods

Environment

• Connector : SQLServer
• Host: A named instance of your SQL Server database
• Connection Method: Proxy Agent

Resolution

To resolve this issue, configure your SQL Server named instance to use a static TCP port, then connect using the Fivetran Proxy Agent. This allows us to establish a secure and stable connection, provided all other networking and authentication requirements are met. For more information, see the Microsoft documentation on configuring SQL Server to listen on a specific TCP port.

If you can't assign a static port, consider using one of the supported connection methods for named instances:

• Direct connection with access safelisted and firewall rules adjusted
• SSH tunnel
• PrivateLink

To learn more, see our Database Connection Options documentation.

Cause

This issue occurs when you provide a named SQL Server instance in the Host field while using the Proxy Agent connection method. Named instances rely on the SQL Server Browser service to dynamically resolve port numbers, but the Fivetran Proxy Agent doesn't support this resolution. Instead, we require a direct host and static port combination, which named instances don't provide by default.