I have also seen {"Logon failed due to unexpected error.\r\n\r\nPlease check if the Sage200Configuration database is configured and running.\r\n\r\n(Message was: The type initializer for 'Sage.Common.IdentityProvider.AuthenticationProvider' threw an exception.)"}
Just for information I have had this running since Sage 2017 year on year no problem. This 2023 R2 is giving me problems.