The HTTP 400 Bad Request error message can be frustrating to deal with. You try to access a website and are met with a vague error message that doesn’t explain what went wrong or how to fix it.
In this comprehensive guide, I’ll explain what causes the 400 Bad Request error, the common variations you may see, and actionable solutions to resolve it for good.
Table of Contents
- What is a 400 Bad Request Error?
- Common Variations of the 400 Error Message
- 12 Solutions to Fix a 400 Bad Request Error
- 1. Check the URL for errors
- 2. Try refreshing the page
- 3. Clear your browser cache
- 4. Use alternate browsers and devices
- 5. Disable browser extensions
- 6. Clear out cookies
- 7. Flush your DNS
- 8. Check the file size
- 9. Use a VPN or alternate network
- 10. Test alternate devices
- 11. Disable proxies and filters
- 12. Contact the site owner
- Preventing 400 Errors in the Future
- Key Takeaways on Fixing 400 Errors
What is a 400 Bad Request Error?
The 400 Bad Request error is an HTTP status code that means the request sent by the client (e.g. your browser or application) was malformed or otherwise unintelligible by the server.
Some common causes behind a 400 error include:
- Typos in the URL
- Invalid syntax or invalid characters in the request
- Expired cookies or corrupted browser cache
- File size limitations when uploading data
- Issues with browser extensions
The key thing to understand is that a 400 Bad Request error means the issue is with the client request rather than the server. It’s a client-side error.
That means troubleshooting steps need to focus on your device, browser, or application rather than issues with the website’s server.
Common Variations of the 400 Error Message
While the underlying cause of a 400 error is always the same, the exact error message you see may vary slightly across browsers and websites.
Some common variations include:
- HTTP Error 400 – Bad Request
- HTTP Error 400
- HTTP Status 400 – Bad Request
- 400 Bad Request
- Bad Request – Error 400
- 400 Bad Request – Invalid URL
The core message is fundamentally the same. The server cannot understand or process the request sent by the client.
12 Solutions to Fix a 400 Bad Request Error
Whenever you encounter a 400 bad request error, there are a number of troubleshooting steps you can take to resolve it:
1. Check the URL for errors
Carefully check the URL you were trying to access for any typos or incorrect characters. Delete and retype the URL from scratch rather than copying and pasting.
2. Try refreshing the page
Sometimes a basic refresh clears up a one-off glitch. Click the refresh icon or press F5 to reload.
3. Clear your browser cache
An outdated or corrupt browser cache can result in a 400 error. Clear your browser data and cache entirely.
4. Use alternate browsers and devices
Try loading the same URL in different browsers and devices. If the error only occurs in one place, it indicates an issue with that browser or device rather than the server.
5. Disable browser extensions
Some browser add-ons can interfere with page requests and functionality. Disable all extensions then try to re-access the URL.
Clear all browser cookies then attempt to reload the page. Corrupted or outdated cookies may be interpreted incorrectly by the server.
7. Flush your DNS
An outdated DNS cache can cause sites to be inaccessible. Flush your DNS to eliminate any mismatches.
8. Check the file size
When uploading a file, verify the file size is within the allowed limits. Overly large files may trigger a 400 error.
9. Use a VPN or alternate network
Connect via an alternate network connection with a VPN to determine if the issues are network-related.
10. Test alternate devices
Try the accessing the URL on entirely different devices like mobile phones. If the error occurs across devices, it likely server-related.
11. Disable proxies and filters
Some security tools and filters can block access at the network-level. Disable any proxies, filters, or firewalls temporarily as a test.
12. Contact the site owner
If the error persists after trying the above troubleshooting, get in touch with the site owner to determine if there are any known server issues.
Preventing 400 Errors in the Future
While occasional 400 errors will happen to anyone from time to time, you can take measures to minimize how often you see them:
Double check URLs: Carefully type or copy/paste URLs rather than typing them out offhand. Always verify there are no typos or extra characters.
Regularly clear browser data: Set a reminder to routinely clear your browser cache and cookies to prevent corruption issues.
Keep software up-to-date: Using the latest browser and OS versions improves stability and prevents bugs that lead to 400 errors.
Use a pop-up blocker: Some pop-ups and ad redirects can unexpectedly send malformed requests resulting in a 400 error code.
Go incognito for sensitive transactions: Open a private browsing session before accessing any sites that involve entering sensitive data or making financial transactions.
Key Takeaways on Fixing 400 Errors
The key points to remember when dealing with a 400 bad request error:
- It’s a client-side error – something with the request rather than the server
- Multiple troubleshooting steps focus on your browser, device, or network
- The error message wording might vary slightly but the cause is the same
- Occasional 400 errors happen but you can take measures to prevent them
Understanding what’s behind a 400 bad request error makes it far less frustrating when you encounter one. You can methodically troubleshoot the potential causes and rectify it faster.
Implementing browser best practices and secure browsing habits minimizes how often you see them occur in the first place as well.
