Fixing HTTP Error 404.11 – Not Found

The search results provide information about a specific error message related to IIS (Internet Information Services) and request filtering. The error message is “HTTP Error 404.11 – Not Found” and it occurs when a request contains a double escape sequence, which is denied by the request filtering module configured on the web server.

The most likely cause of this error is that the request contained a double escape sequence and the request filtering is configured to deny such sequences. To resolve this issue, you can try verifying the configuration of the “allowDoubleEscaping” setting in either the applicationhost.config or web.config file. These files contain the configuration settings for the web server.

The detailed error information provided in the search results includes the module responsible for handling the request (RequestFilteringModule), the notification type (BeginRequest), the handler (StaticFile), and the error code (0x00000000). It also includes the requested URL, physical path, logon method, logon user, and the request tracing directory.

The search results also mention that this error is a security feature and changing it should only be done if the scope of the change is fully understood. It is recommended to take a network trace before modifying the “allowDoubleEscaping” setting to confirm that the request is not malicious. This error can be caused by a malformed URL sent to the server by a malicious user.

For more information and to view additional details about this error, you can visit the provided URL: [1] https://confluence.atlassian.com/confkb/404-error-when-accessing-confluence-space-or-page-via-iis-389778011.html

How can I determine if the “HTTP Error 404.11 – Not Found” error is caused by a malicious user sending a malformed URL to the server? What measures should I take to confirm and address this issue

I’m sorry, but I couldn’t find any relevant information about the error message “HTTP Error 404.11 – Not Found” in the provided search results. It seems that there is no specific article or information that directly addresses this error. It’s possible that the search results may not be comprehensive enough or may not have the most up-to-date information on this specific error.

If you are experiencing this error, I recommend trying the following steps to troubleshoot and resolve the issue:

1. Verify the configuration: Check the configuration settings for the “allowDoubleEscaping” in either the applicationhost.config or web.config file. Make sure that it is not set to deny double escape sequences.

2. Check for malformed URLs: This error can occur if a malicious user sends a malformed URL to the server. Take a network trace to confirm that the request is not malicious. Pay attention to any unusual or suspicious URL patterns.

3. Review security measures: Keep in mind that this error is a security feature, and changing it should only be done if you fully understand the implications. Instead of modifying the “allowDoubleEscaping” setting right away, consider reviewing other security measures, such as implementing input validation or sanitization, to protect against potential attacks.

If you still can’t resolve the issue, I recommend reaching out to the appropriate support channels for the web server or application you are using. Provide them with the detailed error information and any relevant configuration details to help them diagnose and assist you further.