ASP.NET Page says I need to reference an assembly that does not exist!

Question

My asp.net site has to run on several client servers. It's working fine on a majority of them, but a couple have run into an error message on a few pages:

Compiler Error Message: CS0012: The type 'MetaNameValuePair' is defined in an assembly that is not referenced. You must add a reference to assembly 'App_Code.t_3vcono, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null'.

The type 'MetaNameValuePair' is actually defined in a .cs file within my App_Code folder, not an external assembly. Is it failing to compile that .cs file?

Answer 1

Attempt 1:

A similar question was asked a couple of months back and look at those answers.

Attempt 2:

Have you cleared the "Temporary ASP.Net Files" for the site, usually found at C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files? There may be an old copy lingering around.