A connection was successfully established with the server, but then an error occurred during pre-login handshake (provider-TCP Provider; error-0

[Paraman]

Hi, from my C# windows application, when I try to connect with my SQL Database, located in my website, I receive the following error message

A connection was successfully established with the server, but then an error occurred during pre-login handshake (provider-TCP Provider; error-0 An existing connection was forcibly closed by the remote host.)

My Connection String

String MyDBCon_1 = "Server=xxx.xxx.xxx.xx, xxxx; User Id=MyUserID; Password=MyPsWord; Database=MyDataBaseName;";

 

[Skydiver]

What happens when you temporarily disable all your anti-virus software?

Have you verified that both your machine as well as the database server is using the latest SSL/TLS, and has disabled obsolete SSL/TLS versions? I ask because I think we briefly saw this last year when half our machines were still using TLS 1.1 while the other half had finally disabled it.

 

[Skydiver]

Also, if you are using .NET Framework 4.5.2 or older, it defaults to a TLS version that is obsolete. Make sure you are using 4.6.2 or higher. I recommend 4.8.1.