400 Bad Request

  • foodaffairs

    (@foodaffairs)


    1 week, 1 day ago

    Hi,
    this is probably not the correct topic, but I honestly don’t know where else to ask, so please bear with me.

    I’m not a webmaster, just a simple publisher who uses WordPress every day to publish news on my website [Double domain removed]

    I’m writing because I’ve tried everything without solving the issue, and you are my last hope.

    The problem, in short:
    for weeks now, every time I try to access WordPress from ALL the PCs I have available, I get the following error message:

    “400 Bad Request
    Your browser sent a request that this server could not understand.
    Size of a request header field exceeds server limit.”

    I have already tried all the solutions commonly suggested online:
    – clearing browser cache (chrome://settings/privacy?search=cache)
    – changing browser
    – flushing the PCs’ DNS cache
    – going into Chrome Inspect/Application and clearing everything possible
    – working in Incognito mode, which works for a while and then returns “Bad Request”
    – disabling browser extensions

    Result: still 400 Bad Request.

    Please help me solve this issue, otherwise I literally won’t be able to work anymore.

    Thank you,
    Roberto

    The page I need help with: [log in to see the link]

Viewing 2 replies - 1 through 2 (of 2 total)
  • Saurabh – WPMU DEV Support

    (@wpmudev-support7)

    1 week, 1 day ago

    Hello @foodaffairs,

    The issue seems to be almost certainly happening due to some kind of cache buildup, since you also noticed that it works for a while when using Incognito mode.

    Since you already tried clearing the Browser cache and DNS cache, could you please confirm if you have any Performance optimization/cache plugins installed on the site? Based on the website’s source code, I noticed W3 Total Cache. Can you please clear the caches from that plugin and temporarily deactivate the plugin to see if the issue is resolved?

    If not, I would also suggest checking with your hosting support for any server-level cache and clearing it to see if that helps.

    Kind Regards,
    Saurabh

    jamienuminix

    (@jamienuminix)

    1 week, 1 day ago

    Hi @foodaffairs,
    Another angle to look at, the 400 error with “request header field exceeds server limit” almost always means an oversized cookie, may be not cache or extensions.
    I noticed you cleared everything in Chrome’s Application tab, that may have included cookies, but you may try this more targeted approach:
    Go to chrome://settings/cookies → search for your domain → delete everything there specifically. Then try logging in fresh.

    A few more things to try (if you haven’t yet):
    Test on a different device and network
    Phone on mobile data (not home WiFi) is ideal. If it works there, the issue is tied to something stored on your usual devices or network.

    If clearing cookies doesn’t fix it permanently, contact your host your site and tell them you’re getting a “Size of a request header field exceeds server limit” error. They can raise the LimitRequestFieldSize value, should be a quick config change for them.

    And yeah, like what @wpmudev-support7 said, check for a caching or security plugin. W3 Total Cache is there, try deactivating them temporarily. Some plugins write heavily to cookies and could be causing the bloat.

Viewing 2 replies - 1 through 2 (of 2 total)

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