Why are changes to my applicaionHost.config not showing up in IIS?

By | 2017-01-24T09:54:18+00:00 June 13th, 2014|IT Services|

For large or repetitive tasks in IIS (migrating sites, adding additional site bindings, etc.), modifying the applicaionHost.config can prove to be much simpler and efficient than using IIS Manager .  However one of the things I often hear from web administrators is “why are the changes I have made in the applicationHost.config not showing up in IIS”.  Though there could be multiple reasons for this, the most common reason is using a 32 bit editor to modify the applicationHost.confg on a 64 bit OS.  That’s right, if you use a 32 bit editor such as Notepad++ to edit your applicationHost.config in ‘C:\Windows\System32\inetsrv\config’ directory, you are actually opening/saving the applicationHost.confg in ‘C:\Windows\SysWOW64\inetsrv\Config’ regardless of what the title bar or save path may suggest in your editor.  This can lead to a lot of unnecessary confusion and troubleshooting if you don’t understand the fundamental concept of what is actually going on here.

Don’t believe?  Give it a try…

On a 64 bit server with IIS, browse to ‘C:\Windows\System32\inetsrv\config’ and open applicationHost.config using a 32 bit editor such as Notepad++.

Add some text to the comment section of the file and save.


Close Notepad++ and open the same file with a 64bit editor such as Windows Notepad.

Notice your change isn’t there.



Now browse to ‘C:\Windows\SysWOW64\inetsrv\Config’ and open applicationHost.config with Windows Notepad.  Notice your change was saved in this file.




In summary, when editing your applicationHost.config in a 64 bit OS, always be sure to use a 64 bit editor.

About the Author:

Mike Ratcliffe
Mike Ratcliffe is a hard working, self motivated system administrator who adapts quickly to new technology, concepts and environments. With over a decade of experience in information technology and having held numerous titles and responsibilities throughout his career, he currently focuses on system administration of Microsoft Active Directory and related technologies, Microsoft Exchange as well as VMware virtualization.