I'm currently experiencing an issue on a Windows Server 2012 R2.
In the event log is an Error for the Source "Schannel". The error description is:
"A fatal alert was generated and sent to the remote endpoint. This may result in termination of the connection. The TLS protocol defined fatal error code is 40. The Windows SChannel error state is 1205."
I've looked over the articles found through a Google search, indicating it is a problem with SHA512 support. What confuses me is that this error happens randomly and causes a .NET web-site running on the server to fail by not being able to connect to an external web service using SSL TLS 1.2.
The site and communication to the external web service runs fine for weeks, then suddenly this error appears, and the web site cant connect to the web service. The error log from .NET if it helps is "System.Security.Cryptography.CryptographicException: Object contains only the public half of a key pair. A private key must also be provided.".
Without doing anything at all, the problem goes away after 5-10 mins.
Does anyone have any advice on how to debug this issue?
