How to fix an Error 400 client has issued a malformed or illegal request. That’s all we know.

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Today, when I clicked a link in an App, instead of opening a YouTube video, my Edge browser showed the message – ‘Error 400. Your client has issued a malformed or illegal request. That’s all we know.’

Until today, I worked around the error by using Edge in InPrivate mode to view the website.

But, for some reason (maybe a Grace), I used Bing to see how others fixed the problem.

I found this link useful, https://appuals.com/fix-youtube-error-400-client-has-issued-a-malformed-or-illegal-request/, but the instructions were written for Google Chrome users.

So, I adapted them for my Edge browser and found that the modified version worked.

To 1) ensure I could remember how to fix the issue the next time it came up and 2) to also share the knowledge with others who might be experiencing this problem, I wrote the adapted instructions here.

The steps I used were:

    • Go to the YouTube.com website in the Edge browser
    • Open the Developer Console (i.e. Press F12, or click the Edge menu … -> Developer Tools)
    • Click the menu choice – ‘Debugger’
    • Open the ‘Cookies’ -> ‘www.youtube.com’ folder
    • Then right clicked the first cookie and clicked ‘Delete all cookies’ (shown below)
    • Then refreshed the page
Removing malformed cookies vie the Developer Tool in the MS Edge browser.
Removing malformed cookies via the Developer Tool in the MS Edge browser.

Fortunately, these steps worked and I was able to see the YouTube page again.

Hopefully, the adapted instructions will also work for you. However, if you use a different operating system and browser to me, the steps might not work. I am using Windows 10 with an Edge browser. See how you go.

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