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Bad Request 400

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  • Last reply by cor-el

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Firefox keeps displaying '400 Bad Request Request Header Or Cookie Too Large' when trying to read articles on www.bloomberg.com.

It only happens when using this site and only on Firefox and not on Safari or Chrome.

How to fix this and be able to use Firefox as default browser for this site?

regards, Arjen

Firefox keeps displaying '400 Bad Request Request Header Or Cookie Too Large' when trying to read articles on www.bloomberg.com. It only happens when using this site and only on Firefox and not on Safari or Chrome. How to fix this and be able to use Firefox as default browser for this site? regards, Arjen
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This issue can be caused by corrupted cookies or blocked cookies.


Clear the Cache and remove the Cookies for websites that cause problems via the "3-bar" Firefox menu button (Options/Preferences).

"Remove the Cookies" for websites that cause problems:

  • Options/Preferences -> Privacy & Security
    Cookies and Site Data: "Manage Data"

"Clear the Cache":

  • Options/Preferences -> Privacy & Security
    Cookies and Site Data -> Clear Data -> Cached Web Content: Clear

If clearing cookies didn't help then it is possible that the cookies.sqlite file in the Firefox profile folder that stores the cookies got corrupted.

  • rename/remove cookies.sqlite (cookies.sqlite.old) and when present delete cookies.sqlite-shm and cookies.sqlite-wal in the Firefox profile folder with Firefox closed in case cookies.sqlite got corrupted.

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.