Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I am running an application in IIS 7 as "The Default Web Site" this application is configured to run under an application pool that is running as a .NET 4 application.

As a child application of the Default Web Site I have another ASP.NET application. This application was developed using the .NET 3.5 framework and there can run in an application pool configured to use the .NET 2.0 CLR and Integrated managed pipeline.

The parent application (.net 4.0) runs fine. However I cannot get the child application to work. I have it configured to use it's own, 2.0 Integrated Application Pool.

The error received is: 500.19 - Internal Server Error

Config source:

111:   </system.web>
112:   <system.web.extensions />
113:   <!-- 

I noticed that the 'Detailed Error Information' points to a problem in the parent application's config file.

*Config Error The configuration section 'system.web.extensions' cannot be read because it is missing a section declaration *

I assume that my issue stems from the fact that my .net 2.0 application is inhering the configuration from it's .net 4. parent. Is there a way to host a .net 2.0 application as a child of a .net 4 application??

share|improve this question
You are correct that it is a web.config inheritance problem. – Mufasa Nov 3 '11 at 20:30

You could upgrade your subdomain to use the .Net 4.0 framework.

From what I know, it will be a problem if the parent site uses .Net 4 but your child site uses .Net 2.0. To make it easy, you could run your child site on .Net 4.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.