Tag Archives: https

System.Security.SecurityException Failed to negotiate HTTPS Connection – Fiddler

Hi everyone,

I hit the following error when trying to execute a composed request with Fiddler:

[Fiddler] The connection to ‘abc.com’ failed.
System.Security.SecurityException Failed to negotiate HTTPS connection with server.fiddler.network.https> HTTPS handshake to abc.com (for #32) failed. System.Security.Authentication.AuthenticationException A call to SSPI failed, see inner exception. < The function requested is not supported

All that was required to fix it was to add tls 1.2:

  • Tools
  • Options
  • HTTPS
  • Protocols
  • Add tls1.2 to the end of the list and click ok

Thanks to this link for the info: https://www.telerik.com/forums/some-https-sites-are-unaccessible-when-using-fiddler