Cannot connect to a server by using the ServicePointManager or SslStream APIs after upgrade to the .NET Framework 4.6

To work around this issue, update the server to Tls 1.0, Tls 1.1, or Tls 1.2 because SSL 3.0 has been shown to be unsecure and vulnerable to attacks such as POODLE.

Note If you cannot update the server, use AppContext class to opt out of this feature. To do this, use one of the following methods:

• Programmatically: Must be the very first thing the application does because ServicePointManager will initialize only once. Use the following code example in your application:

  private const string DisableCachingName = @"TestSwitch.LocalAppContext.DisableCaching";
          private const string DontEnableSchUseStrongCryptoName = @"Switch.System.Net.DontEnableSchUseStrongCrypto";
          AppContext.SetSwitch(DisableCachingName, true);
          AppContext.SetSwitch(DontEnableSchUseStrongCryptoName, true);

• By using the AppConfig file for your application: Add the following line to the Appconfig file:
  <AppContextSwitchOverrides value="Switch.System.Net.DontEnableSchUseStrongCrypto=true"/>

For more information about the known issues in the .NET Framework 4.6, see Known issues for the .NET Framework 4.6 .