This error message pops up for every form I'm trying to open in Visual Studio 2015 Community Edition. It happened after windows update.
I also had the same problem with Visual Studio 2017 (on Windows 10) with my solutions stored on Microsoft's OneDrive. What I did to fix this was open my local OneDrive settings, find the Files On-Demand setting, and uncheck that checkbox disabling the Files On-Demand feature.