I have the following code to query google analytics using the C# v2.3 api:
string username = \"SAMPLE@SAMPLE.COM\";
string pass = \"PASS\";
string gkey = \"?key=
I was having the same problem. I'd installed the nuget packages, but get the same error "Could not load file or assembly 'Microsoft.Threading.Tasks.Extensions.Desktop, Version=1.0.16.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified." I tried removing and re-installing the nuget packages to no avail. So, I eventually just searched for the Microsoft.Threading.Tasks.Extensions.Desktop.dll file and it was found in the net40 folder. I copied it to my bin folder and then it worked.