I thought I may have introduced some XAML bug and set about trying to isolate which file it might be, but it doesn't seem to be about any specific file. I even reverted to a previous working version, and get the same errors.
If I edit any XAML file, that file then becomes a new error... same as the following, but for a specific .xaml file name instead of Xamarin.Forms.targets:
/DefaultCollection/_git/AssessmentSystem/AssessmentSystem/packages/Xamarin.Forms.1.2.3.6257/build/portable-win+net45+wp80+MonoAndroid10+MonoTouch10/Xamarin.Forms.targets: error : Error executing task XamlG: Text node cannot appear in this state. Line 1, position 1.
I recently switched Xamarin Studio (for Mac, latest version) to the beta channel to check out the bits announced at Evolve 2014. It was after this switch that it started happening. I switched back to the stable channel, but the problem persists.
I had a couple C# syntax which were not reported, and this seems to be the only error it will report now.
This is a show-stopper for me.
Should I uninstall and reinstall Xamarin Studio? Do I need to roll back to a previous version of Xamarin Forms? I'm not getting any useful signals with which to debug this problem.