When developing for older versions of Dynamics SL, I sometimes use Visual Studio 2013 with the Microsoft GitHub integration. Since GitHub started to require TLS 1.2 in Feb., 2018, sync attempts can return the message, “An error occurred. Detailed message: An error occurred while sending the request.” I was able to easily resolve this on Windows Server 2012 by following the instructions in this post. I opened an elevated command prompt and ran the commands that affect all .Net operations. The next time I ran a sync, it succeeded.