Nested ASP.NET ‘application’ within IIS inheriting parent config values?

I currently have 2 x ASP.NET 3.5 web applications in IIS7 (lets call them WebParent and WebChild).

WebChild is nested within the WebParent listing in IIS7 and is set up as an application (rather than just a virtual directory within WebParent). Both currently use their own (Classic) application pool.

Both WebParent and WebChild have their own fully defined web.config files in their own root directories.

I had assumed that seeing as WebChild is defined as an ‘Application’ within IIS, that it would not inherit anything from the WebParent configuration file. However, despite this configuration, I am seeing errors related to various elements within the web.config already being defined (which is correct, there are a couple items that are in both config files, but I thought they should be treated completely independently from one another)?

Can anyone please clarify why this might be occurring?


Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

The exact solution to your problem will depend on what configuration exception message you are seeing. However, this is a typical problem that can often be solved through use of the inheritInChildApplications attribute on the location element in the web.config for “WebParent”. By wrapping the entire system.web section in a location element as follows, you should be able to eliminate the problem you described:

<location path="." inheritInChildApplications="false">
    <!-- ... -->

With IIS 7, you will also want to wrap the system.WebServer section the same way:
<location path="." inheritInChildApplications="false"> 
    <!-- ... -->

This solution is based on an excellent blog article that I found here.

Method 2

If they are repeated, you’ll have to <remove/> then in the child application web.config first, then add back the element you’d like it it’s place. This is assuming that you’d like to have a different value. If you don’t, then just omit the element. A connection string would be a good example of something that is likely common for all applications – so you only need to specify it in the root.


    <siteMap defaultProvider="AdminSiteMapProvider" enabled="true">
        <remove name="AdminSiteMapProvider"/>
        <add name="AdminSiteMapProvider" description="Admin SiteMap provider" type="System.Web.XmlSiteMapProvider" siteMapFile="~/App_Data/admin.sitemap" securityTrimmingEnabled="true" />

Method 3

I think the inheritInChildApplications=”false” is good for cases where you still want to inherit some part of the configuration from the parent.
In cases where you want to completely stop inheritance (as in this case if I’m correct), I’d suggest to use 2 separate application pools for the 2 apps and then apply a not very well documented setting in the applicationHost.config file as I explained in this question “Entry has already been added” – Two Separate App Pools

<add name="MyAppPool" autoStart="true" managedRuntimeVersion="v4.0" managedPipelineMode="Integrated" enableConfigurationOverride="false">
    <processModel identityType="NetworkService" />

Method 4

Follow Scott’s advise and also ensure that you have right clicked WebChild in IIS and selected Convert to Application.

All methods was sourced from or, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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