Config Error: This configuration section cannot be used at this path

I've encountered an error deploying a site to a server. When trying to load the home page, or access authentication on the new site in IIS, I get the error:

Config Error: This configuration section cannot be used at this path. This happens when the section is locked at a parent level. Locking is either by default (overrideModeDefault="Deny"), or set explicitly by a location tag with overrideMode="Deny" or the legacy allowOverride="false".

More detail can be found here, in Scenario 7 matches my hex error code.

The solution given on the linked site above is to set Allow for overrideModeDefault in the section mentioned in my error, in the applicationHost.config file. In my case, under Security in system.webServer. But if I look at the applicationHost.config on my local computer, where the site is properly deployed already, that section is set to Deny.

If this solution is correct, how is my local instance running just fine with the same web.config? According to my applicationHost.config, that section should be locked, but it's not. I'd prefer to not change the applicationHost.config file, because there are many other sites running on that server. Is there another solution?

I had the same problem. Don't remember where I found it on the web, but here is what I did:

• Click "Start button"
• in the search box, enter "Turn windows features on or off"
• in the features window, Click: "Internet Information Services"
• Click: "World Wide Web Services"
• Click: "Application Development Features"
• Check (enable) the features. I checked all but CGI.

btw, I'm using Windows 7. Many comments over the years have certified this works all the way up to Windows 10 and Server 2019, as well.

You could also use the IIS Manager to edit those settings.

Care of this Learn IIS article:

Using the Feature Delegation from the root of IIS:

You can then control each of machine-level read/write permissions, which will otherwise give you the overrideMode="Deny" errors.

For Windows Server 2012 and IIS 8, the procedure is similar.

The Web Server (IIS) and Application Server should be installed, and you should also have the optional Web Server (IIS) Support under Application Server.

Browse to “C:\Windows\System32\inetsrv\config” (you will need administrator rights here) Open applicationHost.config

Note: In IISExpress and Visual Studio 2015 the applicationHost.config is stored in $(solutionDir).vs\config\applicationhost.config

Find the section that showed up in the “config source” part of the error message page. For me this has typically been “modules” or “handlers”

Change the overrideModeDefault attribute to be Allow

So the whole line now looks like:

<section name="modules" allowDefinition="MachineToApplication" overrideModeDefault="Allow" />

After saving the file, the page loaded up fine in my browser.

Warning: Editing applicationHost.config on 64-bit Windows

You need to unlock handlers. This can be done using following cmd command:

%windir%\system32\inetsrv\appcmd.exe unlock config -section:system.webServer/handlers

Maybe another info for people that are getting this error on IIS 8, in my case was on Microsoft Server 2012 platform. I had spend couple of hours battling with other errors that bubbled up after executing appcmd. In the end I was able to fix it by removing Web Server Role and installing it again.