Problem
In Visual Studio’s SSRS Report Designer, when creating or editing a SQL Server data source using SqlClient connection, the database dropdown list fails to populate and shows “Unknown” or “Unavailable database.” Even manually typing the database name results in connection failure, although the same connection works fine in Report Builder and other tools.
Possible Cause
- Visual Studio SSRS Designer uses a 32-bit .NET SqlClient stack that struggles with SQL Server connections when SQL Browser service or named pipes are blocked or unavailable.
- By default, the connection attempts may use Named Pipes or rely on SQL Browser UDP 1434, which can fail if blocked by firewall or network policies.
- On Windows 11 with SQL Server enforcing encryption/TLS 1.2+, the 32-bit SqlClient runtime in Visual Studio can fail to negotiate secure connections properly without explicit protocol settings.
- Report Builder works because it runs 64-bit and uses modern SqlClient libraries that negotiate connections differently.
Possible Solution
- Force TCP protocol in the connection string by prefixing the server name with
tcp:and specifying the port, e.g.:
Data Source=tcp:myserver,1433;Initial Catalog=mydb;Integrated Security=True;TrustServerCertificate=True;
- This bypasses SQL Browser and Named Pipes, using a direct TCP connection that is compatible with Visual Studio SSRS Designer’s 32-bit runtime.
- Additional fixes may include ensuring .NET Framework 4.x strong crypto registry keys are set for both 32-bit and 64-bit runtimes and installing latest SQL Server client drivers (x86) for compatibility.