Avoid web.config inheritance in child web application using inheritInChildApplications

Solution 1:

As the commenters for the previous answer mentioned, you cannot simply add the line...

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

...just below <configuration>. Instead, you need to wrap the individual web.config sections for which you want to disable inheritance. For example:

<!-- disable inheritance for the connectionStrings section -->
<location path="." inheritInChildApplications="false">
   <connectionStrings>
   </connectionStrings>
</location>

<!-- leave inheritance enabled for appSettings -->
<appSettings>
</appSettings>

<!-- disable inheritance for the system.web section -->
<location path="." inheritInChildApplications="false">
   <system.web>
        <webParts>
        </webParts>
        <membership>
        </membership>

        <compilation>
        </compilation>
      </system.web>
 </location>

While <clear /> may work for some configuration sections, there are some that instead require a <remove name="..."> directive, and still others don't seem to support either. In these situations, it's probably appropriate to set inheritInChildApplications="false".

Solution 2:

It needs to go directly under the root <configuration> node and you need to set a path like this:

<?xml version="1.0"?>
<configuration>
    <location path="." inheritInChildApplications="false"> 
        <!-- Stuff that shouldn't be inherited goes in here -->
    </location>
</configuration>

A better way to handle configuration inheritance is to use a <clear/> in the child config wherever you don't want to inherit. So if you didn't want to inherit the parent config's connection strings you would do something like this:

<?xml version="1.0"?>
<configuration>
    <connectionStrings>
        <clear/>
        <!-- Child config's connection strings -->
    </connectionStrings>
</configuration>

Solution 3:

I put everything into:

<location path="." inheritInChildApplications="false">
....
</location>

except: <configSections/>, <connectionStrings/> and <runtime/>.

There are some cases when we don't want to inherit some secions from <configSections />, but we can't put <section/> tag into <location/>, so we have to create a <secionGroup /> and put our unwanted sections into that group. Section groups can be later inserted into a location tag.

So we have to change this:

<configSections>
  <section name="unwantedSection" />
</configSections>

Into:

<configSections>
  <sectionGroup name="myNotInheritedSections">
    <section name="unwantedSection" />
  </sectionGroup>
</configSections>

<location path="." inheritInChildApplications="false">
    <myNotInheritedSections>
        <unwantedSection />
    </myNotInheritedSections>
</location>

Solution 4:

We were getting an error related to this after a recent release of code to one of our development environments. We have an application that is a child of another application. This relationship has been working fine for YEARS until yesterday.

The problem:
We were getting a yellow stack trace error due to duplicate keys being entered. This is because both the web.config for the child and parent applications had this key. But this existed for many years like this without change. Why all of sudden its an issue now?

The solution:
The reason this was never a problem is because the keys AND values were always the same. Yesterday we updated our SQL connection strings to include the Application Name in the connection string. This made the string unique and all of sudden started to fail.

Without doing any research on the exact reason for this, I have to assume that when the child application inherits the parents web.config values, it ignores identical key/value pairs.

We were able to solve it by wrapping the connection string like this

    <location path="." inheritInChildApplications="false">
        <connectionStrings>
            <!-- Updated connection strings go here -->
        </connectionStrings>
    </location>

Edit: I forgot to mention that I added this in the PARENTS web.config. I didn't have to modify the child's web.config.

Thanks for everyones help on this, saved our butts.