Pressing the Red Button

If you are getting some unexplainable 404 errors when accessing html or asp.net pages in IIS, and have exhausted the more common issues, check out your log file for URLScan errors. URLScan is a Microsoft security tool to help protect Internet Information Server. On your developer environment it might be getting in the way.

How Can I Disable URLScan
1. Go to the Control Panel -> Administrative Tools -> Internet Information Services
2. Click WebSites folder, right click to get Properties
3. Click ISAPI Filters tab, find URLScan in the list, click Remove button, then OK to save
4. From Command Prompt (Start -> Run -> Cmd), type “iisreset”, to restart IIS

How Do I Configure URL Scan
There is a configuration file located here:
<Windows Folder>\system32\inetsrv\urlscan\UrlScan.ini
Additional log files are also stored in that directory.
If you want to keep URLScan on your computer, you can check out Microsoft’s documentation.

How Did It Get Installed
I have no idea in my case. I didn’t bother to look into it further. I am guessing through some Windows Update or some unintentionally clicking.