SQL Management Objects (SMO) Error: Could not load type 'Microsoft.Data.SqlClient.SqlAuthenticationMethod' from assembly 'Microsoft.Data.SqlClient, Version=7.0.0.0, Culture=neutral, PublicKeyToken=23ec7fc2d6eaa4a5'.

If you're trying to use SQL Managent Objects (SMO) with the latest SQL Client (v7.0.0) then you might notice the following error:

Could not load type 'Microsoft.Data.SqlClient.SqlAuthenticationMethod' from assembly 'Microsoft.Data.SqlClient, Version=7.0.0.0, Culture=neutral, PublicKeyToken=23ec7fc2d6eaa4a5'.

This is a coding issue that's being tracked here - a new package should be available (currently 9th April 2026).

https://github.com/dotnet/SqlClient/issues/4064