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Help on Error 400

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  • 1 has this problem
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  • Last reply by FredMcD

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When I try to get into my school's faculty website, I get this error (that just started today): "HTTP Error 400. The size of the request headers is too long." Is there a way to fix this?

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Many site issues can be caused by corrupt cookies or cache. In order to try to fix these problems, the first step is to clear both cookies and the cache. Note: This will temporarily log you out of all sites you're logged in to. To clear cache and cookies do the following:

  1. (Firefox 57 and above) Click the Library button 57 library icon and choose History.
    (Click the menu button New Fx Menu and choose History in older Firefox versions.)
  2. In the History menu, choose "Clear Recent History...".
  3. Under "Time range to clear", select "Everything".
  4. Now, click the arrow next to Details to toggle the Details list active.
  5. From the details list, check Cache and Cookies and uncheck everything else.
  6. Now click the "Clear Now" button.

Further information can be found in the Delete browsing, search and download history on Firefox article.


If that doesn't help, you can also try clearing your DNS cache on your computer.

To do this, first press the Windows Key + R and enter ipconfig /flushdns. Then go to the Firefox about:config page and find the network.dnsCacheExpiration preference. Set it to 0 and restart Firefox.

When Firefox starts again, go back to that preference can press the little reset button on the right side to reset it back to the default value. Then restart Firefox again.

Hope this helps.

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web search: https://www.bing.com/search?q=HTTP Error 400 A 400 Bad Request error happens when a server cannot understand a request that’s been made of it.

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