If you’ve ever encountered the confusing message “The custom error module does not recognize this error” while trying to access web-based services like Outlook or Office 365. This error can be easily fixable.
In this article, we’ll break down what causes this error, how users have successfully resolved it, and what steps you can take to fix it.
What Does This Error Mean?
This message usually appears when:
- A web application (like Outlook Web App or Exchange OWA) tries to return an unrecognized HTTP status code, and
- The server (often IIS) doesn’t know how to handle it.
In simpler terms: The system hit an unexpected error, and there’s no predefined response to show you a proper error page—so it throws this vague message instead.
Common Scenarios Where This Occurs
- Signing in to Outlook.live.com or Outlook Web App
- Accessing delegated calendars on Exchange Server
- Using Chrome, Edge, or another browser that stores conflicting session cookies
- Connecting personal Office 365 with a business Office 365 account
How to Fix “The Custom Error Module Does Not Recognize This Error”
Here are proven solutions that have worked for many users:
1. Check Outlook or Server Status
Sometimes the issue isn’t on your end.
- Go to Outlook Service Health or search “Outlook server status.”
- If everything is green, proceed with local fixes.
2. Clear Browser Cookies (but not all)
This has resolved the issue for many using Chrome:
- Click the lock icon in the browser’s address bar.
- Choose Cookies → remove all except the one for
outlook.live.com. - Reload the page.
In many cases, a stray cookie from another site (like your employer’s domain) conflicts with your login session.
3. Switch Your Browser
If Chrome gives you this error, try:
- Firefox – many users report this bypasses the issue
- Microsoft Edge – if you’re using Firefox or Chrome
This is a quick and easy way to confirm if it’s a browser-specific problem.
4. Perform Disk Cleanup
Clearing temporary files can remove lingering session data:
- Search “Disk Cleanup” on Windows.
- Select all options and hit OK.
- Restart your browser and try accessing the site again.
5. Refresh the URL Manually
Sometimes, simply placing your cursor at the end of the URL and hitting Enter again can re-trigger the request successfully.
6. Advanced Fix for Exchange Server Users
If you are in an enterprise environment:
- This error is known to occur when using OWA web parts to access delegated calendars in Exchange Server 2013/2010 environments.
- Microsoft suggests installing Cumulative Update 11 for Exchange Server 2013 to resolve it.
Why Does This Happen?
This error typically occurs due to how web servers like Microsoft IIS handle unexpected HTTP responses. Custom error modules are designed to display user-friendly error pages when something goes wrong. However, if the server encounters a status code it hasn’t been configured to process—such as an uncommon or application-specific error—it doesn’t know how to respond properly.
| Fix Method | Effectiveness | Difficulty |
|---|---|---|
| Delete stray cookies | High | Easy |
| Switch browsers | High | Very Easy |
| Disk Cleanup | Moderate | Easy |
| URL Refresh | Quick Fix | Very Easy |
| Exchange Server Update | Enterprise | Advanced |
Conclusion
While the “custom error module does not recognize this error” message might seem like a dead-end, it’s often caused by simple issues like cookie conflicts or browser sessions. With the steps above, most users can fix the problem in minutes—no tech degree needed.
If you’re still stuck, try accessing the service on a different device or network. And if you’re in a corporate environment, contact your IT team to check for Exchange server updates or policy restrictions.
Have you faced this error recently? Let us know in the comments what worked for you.
