Compiler Error Message: BC30560: 'xxxxxxxx_aspx' is ambiguous in the namespace 'ASP'

I get this error after 开发者_Go百科installing a web site on a test server using an msi.

This is similar to this SO question. However, that question was related to the development environment, so it does not solve my problem.

Anyboby knows what causes this error?

Most common reason would be that you have multiple versions of some class in your web app... which of course can happen when multiple assemblies contain the same class. Or by inadvertently mixing precompiled and on-the-fly compiled aspx pages.