I started working with Visual Studio 2015 tonight and ran into an error. The website I’m building is a test site for Azure, but the target framework for the site was .NET Framework 4.6 (which Azure does not yet support for Web Apps). I downgraded the target framework to 4.5.2 and the website compiles correctly, but when I go to run in browser, I receive an error:
Initially I tried changing the version in Properties > Build > Advanced, but that was not solving the issue.
This error is corrected by changing compiler settings in the web.config.
Changing langversion to 5 will allow the site to compile on Azure and in .NET 4.5.2.