My Xamarin development was working fine yesterday and is now showing this error message when trying to run the project:
error MT1108: Could not find developer tools for this 10.0.2 (14A456) device. Please ensure you are using a compatible Xcode version and then connect this device to Xcode to install the development support files.
I have updated Xcode to 8.1, Xamarin Studio is on the latest stable build and I've upgraded to macOS Sierra, but I still have this issue. Colleagues with the same dev environment as me are still able to run the project fine. I'm also able to open a different iOS project with the same settings and it will deploy to the phone fine.
Other things I've tried:
Complete uninstall/re-install of Xamarin Studio.
The Alpha build of Xamarin Studio.
So this worked for me: