How to Fix: Your client has issued a malformed or illegal request?

400 Bad Request: Your client has issued a malformed or illegal request that occurs when we try accessing the webpage that isn’t available or we have requested a secured page without proper credentials. Verifying the URL and using proper credentials after clearing cookies and cache should easily fix the bad request error.

The inability to access a website could be due to various reasons. While errors could attribute some of them to the server-side, a few could well be related to the problems arising from the client, aka user. And the Error 400 belongs to the latter half.

The accompanying error message reads Bad Request – Your client has issued a malformed or illegal request, which concretes our above statement. As a result, while the request leaves your PC, it wouldn’t be able to be carried forward by the servers.

Your client has issued a malformed or illegal request

So what could be the reason for this issue? An incorrect URL or a browser using an outdated browser cache or stored DNS records are the two most common causes of the error, as mentioned above.

While the issue is no doubt quite concerning and irritating in equal measures, fortunately, some workarounds are known to rectify this issue. And this guide shall make you aware of just that.

Recheck URL Format

One of the primary reasons for this issue is the entering of incorrect URLs by the user. In this regard, you should double-check the spelling of the website if you have mistakenly used backslashes instead of the forward slashes or have incorporated an unsupported symbol such as curly brackets in the hyperlink.

Furthermore, although the name of the site isn’t case sensitive, its directory might be. Just verify that everything entered after the .com domain is exactly as it should be. Keep these points in mind and see if you can access the site.

Try Incognito Mode

It is no hidden secret that third-party add-ons could lead to various types of 4XX errors. Therefore the safest bet is to browse the web in private mode in chrome. Doing so will disable all the extensions, and if it fixes the issue as well, then the next course of action is to disable or remove the newly installed add-ons.

Here are the steps to open the incognito mode in chrome:

  1. Launch Google Chrome browser.
  2. Keypress the Ctrl + Shift + N shortcut keys to open an Incognito Window.
    Use Google Chrome Incognito
  3. Now try accessing the site that was causing the bad request error.

If it loads without any issue, then the problem could presumably be attributed to the installed extensions or cookie and cache clutter within the browser.

Disable Browser Extension

Most of the issue while access the browser is generally caused due to extensions that we have installed. Even I faced the issue with the website not loading properly and found the extensions are the culprit. I think these browser extensions could result in malformed or illegal requests.

Here are the quick steps to disable browser extensions in chrome:

  1. Launch Google Chrome browser on the computer.
  2. Visit the chrome extensions pages at chrome://extensions/ address.
  3. Toggle the button to disable the extension.
    Disable browser extensions on chrome computer
  4. Now disable each of the extensions, one at a time, until the error has been fixed.

Moreover, it is recommended to uninstall the extensions that issue causing extension right away.

While these add-ons tend to add more functionalities to the browser, they could sometimes lead to a few problems. As and when that happens, it is better to bid farewell to that extension.

Delete DNS Cache

DNS acts as a record book that keeps a hold of all the Domain Names corresponding to their IP Addresses. But if this data gets outdated or corrupted, the browser wouldn’t establish a successful connection to the web. Therefore, it is recommended to delete the temporary cached data.

Here are the steps to clear DNS cache from the Windows OS:

  1. Open the Start Menu and search CMD.
  2. Launch the Command Prompt as an administrator.
    Run Command Prompt as Administrator
  3. Now type in ipconfig /flushdns, and hit Enter.
    Flush DNS and IPConfig in Windows command prompt

This will delete the DNS cache, and hopefully, the lousy request would rectify the issue.

Flushing the DNS might delay the loading of the website the next time you visit them. However, this is just a one-time delay and would be rectified as soon as the cache data is re-populated.

Delete Browser Cache and Cookies

Over the due course of time, a lot of temporary data in the browser gets accumulated. This not only slows down the browsing experience but could also conflict with the proper loading of websites. So should consider deleting these cache and cookies files at the earliest.

Here are the steps to clear browser cache and cookies:

  1. Launch the Chrome browser.
  2. Type in delete cache  chrome actions in the address bar.
  3. Click on Clear Browsing Data from the drop-down menu.
    Clear browsing data Google Chrome Actions
  4. Select Cookies and other site data and Cached images and files.
    Clear Cookies and Cache from Chrome Browser
  5. Hit on the Clear data button and wait for the process to complete.

Check if it fixes the 400 Bad Request Error within the browser.

Deleting the cookies might erase some of the saved information. Likewise, deleting the cache would translate to the browser asking for a few extra seconds before loading a site. But both of them should be along the fine lines if they fix the underlying issue.

Verify File Size

If you are getting this error while trying to upload a file, then it could be due to the maximum file size restriction placed by that site. So consider compressing this file to a RAR or ZIP format before uploading it over to the web. Or, if possible, upload the file to clouds and then share the link with the concerned party.

Bottom Line: Fix 400 Bad Request

So this was all from this guide on how you could fix the 400: Bad Request – Your client has issued a malformed or illegal request error. We have shared five different methods for the same.

In my case, the DNS cache wasn’t in sync with the online records. As a result, the browser was still picking up old pieces of data and, in turn, couldn’t establish a successful connection. Deleting these Domain Name Server cache proved to be the savior in my case.

Do let us know in the comments which one spelled out success for you. Also, share if you have tried anything that worked to fix the issue.

Lastly, here are the recommended web browsers for your computer and mobile phone that you should give a try.

WindowsMacOSiOSAndroidLinux
Chrome WindowsChrome MacChrome iOSChrome AndroidFirefox Linux
Firefox WindowsSafari MacSafari iOSEdge AndroidChrome Linux
Edge WindowsFirefox MacEdge iOSSamsung InternetEdge Linux

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