I just installed the release version of Visual Studio 2010, and it looks like there's something wrong with the standard ASP.NET server controls.
When I create a basic server control, such as a TextBox, the editor underlines it in green and says (I also get no intellisense for ASP.NET controls):
Element 'TextBox' is not a known element. This can occur if there is a compilation
error in the Web site, or the Web.config file is missing.
The web site builds fine, and the Web.config file is not missing:
<?xml version="1.0"?>
<configuration>
<system.web>
<compilation debug="false" targetFramework="4.0" />
</system.web>
</configuration>
The controls work just fine in the code-behind, and they function correctly when I run the site.
Is there some configuration problem here?
This person who's a tester on the Visual Web Developer Team offered this workaround, which apparently worked:
Close VS, delete schema cache, and re-open VS. You can find the schemas under something like:
C:\Users\Pavel\AppData\Roaming\Microsoft\VisualStudio\10.0\ReflectedSchemas
It is safe to delete all files in this folder.