When running up DNN on Windows 10 / IIS 10 I get this error below.  I can find the section to edit in the applicationHost.config file but of course can't save it even with running Notepad as an administrator.

The error seems to imply that the handlers section is locked at the global level and no config file below this level may override it.  This is daft ... DNN won't work with the <handlers> section disabled and with no way to override.

Read over this material: https://www.iis.net/learn/get-started/planning-for-security/how-to-use-locking-in-iis-configuration but it fails at one point -- no way to save the file after editing.

This is either a red herring or one heck of a stonewall by Microsoft to prevent people from harming their computers.  The file needs to be edited.  How is this done?

Here is the section in the applicationHost.config:

        <sectionGroup name="system.webServer">

            <section name="asp" overrideModeDefault="Deny" />

            <section name="caching" overrideModeDefault="Allow" />

            <section name="cgi" overrideModeDefault="Deny" />

            <section name="defaultDocument" overrideModeDefault="Allow" />

            <section name="directoryBrowse" overrideModeDefault="Allow" />

            <section name="fastCgi" allowDefinition="AppHostOnly" overrideModeDefault="Deny" />

            <section name="globalModules" allowDefinition="AppHostOnly" overrideModeDefault="Deny" />

            <section name="handlers" overrideModeDefault="Deny" /> <-- need to set to 'allow' or put it in an unlocked section at the end of the file.

            <section name="httpCompression" overrideModeDefault="Allow" />

            <section name="httpErrors" overrideModeDefault="Allow" />

            <section name="httpLogging" overrideModeDefault="Deny" />

   92:     </modules>
   93:     <handlers>
   94:       <remove name="WebServiceHandlerFactory-Integrated" />

The problem is IIS was not fully set up on my new machine.

The settings that are in IIS on my old machine match those that were in my new machine.  So there's no reason it should not have worked.

Apparently Windows 10 Pro assumes an end user isn't doing any dev work by default.  And if one doesn't specifically set up IIS in the latest and greatest update of Windows 10 you're just locked out and get goofy errors.

In Windows Features / IIS I had to specifically select ASP.Net 3.5 and ASP.Net 4.7, which in turn selected the correct defaults.  Then applying the changes got me to the next steps to clean up to get the site working in local host.

Just in case someone else runs into the same trouble.