“Unhandled Extension Element” in WIX (Windows Installer XML)

I’m using WIX to create an MSI for a web application, part of the installer needs to create the IIS settings, so i’m using the WIX IIS extensions. I started off by adding the namespace:


Everything looked good, i was getting Intellisense within VS 2010, but then when i tried to build the MSI package, i got this error:

The Component element contains an unhandled extension element ‘iis:WebSite’.  Please ensure that the extension for elements in the ‘http://schemas.microsoft.com/wix/IIsExtension’ namespace has been provided.

I took a while to figure it out…in order to fix this issue, i had to add a reference to WixIisExtension.dll to my WIX project.  You add the reference just like you would add one for any other project. 

About esteban

Esteban is the Founder and Chief Technologist at Nebbia Technology, an ALM consulting and Azure-powered technology company. He is a software developer with a passion for ALM, TFS, Azure, and software development best practices. Esteban is a Microsoft Visual Studio ALM MVP and ALM Ranger, Pluralsight author, and the president of ONETUG (Orlando .NET User Group).

10 thoughts on ““Unhandled Extension Element” in WIX (Windows Installer XML)

  1. Anonymous

    Thanks a lot mate. u saved lot of time for me.

  2. HowitZer

    How do you add the extension reference in a .wxs file?

  3. Dave

    Thanks Esteban! I’m new to WiX and this was driving me nuts!

    1. esteban

      Awesome, glad it helped!

  4. Comara

    You just saved HOURS with this one….thank you.

    1. esteban

      No problem!

  5. Rakesh

    Also make sure that -ext WixIISExtension is added to both candle and light commands.

  6. Franci

    Thank you so much, you saved my life 🙂

  7. harshal


  8. Vic


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