HttpWebRequest results in: "Request was aborted: Failed to create SSL / TLS secure channel" and returned code = AlgorithmMismatch
As mentioned in this post I have exactly the same error in network logs (return code = Mismatch algorithm), except that I am using
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12
to avoid POODLE vulnerability, regkey is set to 1 (.. \ Protocols \ SSL 2.0 \ Client), but I still get this error. My SSL certificate has been added to Firefox and the secure web service is available and works fine. I am exactly this error occurring in two environments (Windows Server 2012 and Windows 7) and with a test SSL certificate everything works fine. Any ideas?
source to share
..\Protocols\SSL 2.0\Client
That the key is wrong to enable TLS1.2 (SSL * 4 ** was renamed to TLS1.0 during development, SSL2 is much older, fundamentally broken and should never be used).
The correct keys are listed on the MS KB page: https://support.microsoft.com/en-gb/kb/245030
But you need to set the values in the keys including:
…\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Server
(And there are tons of simplified setup guides.)
Even though both client and server can agree on the TLS1.2 protocol suite, there are still issues that will cause the secure channel to fail (for example, the client does not trust the server's certificate). This will require more details (start with the exception type and message, and for internal recursive exceptions).
source to share