The upgrade to new versions of Xamarin Studio worked great coming down. But immediately afterwards, deploying to my android devices stopped working. The common error was "Deployment Cancelled. Internal error."
After much head-scratching, and pounding on the desk - and the help of the other Xamarin developer (he's iOS, I'm Android) - we discovered the following steps are necessary (after upgrading to a new version of Xamarin Studio).
1) Remove all Mono shared runtimes from your device -> cruicial. 2) Remove previous versions of the software being developed. 3) Clean and Rebuild your project from scratch.
After that, you should be able to deploy debug runtimes to your devices.