While working with VS 2008, I was getting this warning all through my asp .net code in addition to having no intellisense for any asp controls.
If I added the
tag to my child pages, intellisense would come back. I saw a lot of other posts relating to VS 2005 which said to keep the master page open, but that didn’t work.
I had to do the following to get intellisense back:
1. Remove the masterPagefile setting in web.config
2 Delete everything from C:\Documents and Settings\[Username]\ApplicationData\Microsoft\VisualStudio\9.0\ReflectedSchemas
3. Add MasterPageFile=”[master page file name]” to the top of each child page.