How do I fix the “compilerVersion” IIS error?

Question

I\'m getting this exception:

System.Configuration.ConfigurationErrorsException: The value for the \'compilerVersion\' attribute in the provider opti

Answer 1

In my case, I was trying to run a child application using 4.0, but the parent application needed to still use 2.0. Wrapping the compilers information in the parent web.config with a tag fixed it.

Parent Web.config: