TLS Exception. Unknown Secure Transport error '

问题:

I keep getting this error Unknown Secure Transport error 'ClosedGraceful' even though my ServicePointManager.ServerCertificateValidationCallback is returning true.

The full stacktrace is ...

     at Security.Tls.AppleTlsContext.CheckStatusAndThrow (SslStatus status, Security.SslStatus[] acceptable) [0x000b1] in /Users/builder/data/lanes/3339/39ebb778/source/maccore/src/Security/Tls/AppleTlsContext.cs:170 
  at Security.Tls.AppleTlsContext.Write (System.Byte[] buffer, Int32 offset, Int32 count, System.Boolean& wantMore) [0x0003f] in /Users/builder/data/lanes/3339/39ebb778/source/maccore/src/Security/Tls/AppleTlsContext.cs:883 
  at Security.Tls.MobileAuthenticatedStream.ProcessWrite (Security.Tls.AsyncProtocolRequest asyncRequest, AsyncOperationStatus status) [0x0002f] in /Users/builder/data/lanes/3339/39ebb778/source/maccore/src/Security/Tls/MobileAuthenticatedStream.cs:637 
  at Security.Tls.AsyncProtocolRequest.ProcessOperation (AsyncOperationStatus status) [0x00086] in /Users/builder/data/lanes/3339/39ebb778/source/maccore/src/Security/Tls/AsyncProtocolRequest.cs:199 
  at Security.Tls.AsyncProtocolRequest.ProcessOperation () [0x0000d] in /Users/builder/data/lanes/3339/39ebb778/source/maccore/src/Security/Tls/AsyncProtocolRequest.cs:159 
  at Security.Tls.AsyncProtocolRequest.StartOperation () [0x00000] in /Users/builder/data/lanes/3339/39ebb778/source/maccore/src/Security/Tls/AsyncProtocolRequest.cs:140 

I've even tried adding

<key>NSAppTransportSecurity</key>
<dict>
  <key>NSAllowsArbitraryLoads</key>
  <true/>
</dict>

To info.plist but still no luck

Edit: Currently using RestSharp

回答1:

Change the property iOS Build > Advanced > SSL/TLS implementation from Apple to Mono.

回答2:

The accepted answer was Correct but since the current visual studio is not having that option, we need to enter mtouch argments under iOSBuild-->Code Generation & Runtime-->Additional mtouch arguments