Your client has issued a malformed or illegal request [Fixed]

December 2022 · 5 minute read

YouTube is the most popular video-sharing site in the world. It’s accessed by millions of users every day that upload and search all sorts of video content. Thus, we can say it’s one of the biggest search engines, too.

YouTube was created in 2005, and in October 2006 Google acquired it and transformed it into the giant that is today.

Even though the site is constantly being developed and improved, sometimes some unexpected errors can show up.

That’s the case with Error 400: your client has issued a malformed or illegal request and today we’ll take a look at it.

What is the error 400: Your client has issued a malformed or illegal request?

A lot of users reported the Error 400 on YouTube, and although is an old and known issue, the cause is still a mystery to Google. Let’s find out how to fix it.

Fixing YouTube error 400: Your client has issued a malformed or illegal request, usually involving clearing all the cookies.

The error is mainly caused by shared cookies between YouTube and other extensions. If this action doesn’t solve the problem, you need to clear the specific faulty cookies from Developer tools or use Incognito mode.

It seems that the error is caused by an extension called The Great Suspender. This extension shares the cookies with YouTube and sometimes alters them, leading to the appearance of the Error 400.

How can I fix the error 400 in YouTube?

1. Try the Incognito mode

  • Hit the Windows key, type Chrome, then open the browser.
  • Use the following keyboard shortcut to open the Incognito mode: Ctrl + Shift + N.
  • Now try accessing YouTube and check if the error is gone.

    • If not, do not worry, we have plenty of other solutions you should definitely consider.

    2. Switch the browser

    Even if you may not have thought about it, switching your browser to a different one, might be the best option you should try.

    Opera is one of the most popular browsers of the moment due to the fact that it’s a fast search engine with a built-in ad blocker and a free VPN that keeps your internet experience safe and productive.

    One important aspect of the Opera platform is that it uses less processing capacity than any other browser, this way you are guaranteed to always enjoy smooth online surfing.

    You’ll be delighted with the user-friendly interface that makes it possible to chat and browse at the same time thanks to the built-in messenger on the sidebar of the page.

    Another fun characteristic is the customizing feature that allows you to choose from a variety of themes. You can keep your favorite sites one click away by bookmarking them and saving loads of time.

    ⇒ Get Opera Browser

    3. Clear the cookies from Chrome’s settings

  • Hit the Windows key, type Chrome, then open the browser.
  • In the search bar, input the following location, then hit Enter: chrome://settings/siteData
  • There, type youtube, in the search-bar from the top-right of the page.
  • All the cookies related to YouTube should appear. Click on the Clear all data button.

    • After doing that, check if a Malformed or illegal request message still appears.

    4. Clear cookies using Developer Tools

  • Press on the Windows key, type Chrome, then click on the first result.
  • Navigate to YouTube.
  • In the main YouTube window, use the following keyboard shortcut: Ctrl + Shift + I.
  • Now, the Developer Tools should open in the right side of the window.
  • There, click on the two arrows icon located next to Sources, then choose the Application option.
  • In the left panel, under Storage, expand Cookies.
  • All the cookies should appear.
  • Delete the gsScrollPos-[4-digit number].

    • After following these steps, check if YouTube error 400: Your client has issued a malformed or illegal request message is gone. If not, make sure you keep on reading.

    5. Clear Chrome’s cache and cookies

  • Press on the Windows key, type Chrome, then click on the first result.
  • Use the following keyboard shortcut to open the Clear browsing data page: Ctrl + Shift + Delete.
  • In the Time range section, use the drop-down menu, and choose All Time.
  • Now, checkmark the Cookies and other site data and Cached images and files options.
  • Click on the Clear data button.

    • 6. Clear DNS cache

  • Hit the Windows key, type cmd, then open Command Prompt.
  • Now, input the following command and press on Enter: ipconfig /flushdns
  • This will delete the DNS cache.
  • Then, check if the issue perssits.

    • 7. Reinstall Chrome

  • Use the following keyboard shortcut to open Windows Settings: Windows + I.
  • Go to the Apps section.
  • In the opened window, in the search bar located in the right side, type Chrome.
  • Click on the found result, then choose to Uninstall the browser.
  • After the process is completed, navigate to the Chrome download page.
  • There, click on the Download Chrome button.
  • Follow the on-screen instructions to reinstall the browser.

    • You can also try these easy and general fixes that fixed YouTube error 400 for some users.

    These solutions are relatively simple and you should have no problem-solving Error 400: your client has issued a malformed or illegal request. Remember that The Great Suspender extension is the main cause, but it’s not the only one.

    We’d like to know your thoughts on this subject so feel free to share them in the comments section below.

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