Error in C# app SSPI failed on Windows 10 computers

[Scott Boland]

We have started getting an System.Security.Authentication.AuthenticationException with the message "A call to SSPI failed". The inner exception message is "The Local Security Authority cannot be contacted".

We use the .NET Connector in a C# application. The error happens on the line to Open() the MySqlConnection. We use a self-signed certificate. It may be caused/related to a recent Windows 10 update since it seems to only affect them. Also our apps that use C++ (non .NET) do not have the issue even on the same computer.

Let me know what information may help or if you have any questions. Thanks!