Understanding the “400 Bad Request – Cookie Too Large” Error
So, here’s where I ran into trouble — out of the blue, visiting a site I’ve used for years, and suddenly, bam, “400 Bad Request – Cookie Too Large” pops up. It’s pretty frustrating because it wasn’t obvious what was going on at first. This kind of error shows up quite often in Chrome, Edge, or Firefox, and it basically points to a problem with your browser’s cookies. The main issue is that the website’s stored cookies have become too big or corrupted, and now the browser refuses to send them to the server. If the server’s using something like Nginx, it has limits on cookie sizes — usually around 4 KB per cookie — and if those are exceeded, the request gets rejected with that 400 error.
This tends to happen especially if you keep revisiting the same site regularly and don’t clear your cookies often. Sometimes, site updates or bugs can cause cookies to swell or become corrupted, leading to this annoyance. Honestly, it’s frustrating but fixable — I didn’t get it right away, but it turns out clearing cookies is the main fix. Just be careful, because clearing cookies can reset your login details or preferences if you’re not prepared.
Why Cookies End Up Too Large or Get Corrupted
Cookies are tiny bits of data stored directly in your browser, designed to remember things like your login status, site preferences, or session IDs. Over time, they can pile up — especially if a website keeps creating new cookies without deleting old ones, or if there’s a bug that messes with cookie data. This can cause some cookies to become massive or corrupted. When combined with server limits, the browser simply stops sending them, resulting in the error. Some servers set strict limits on cookie sizes, particularly with configurations like Nginx. Once those limits are hit, the site blocks your request and shows the 400 error.
If you’re wondering why it suddenly started happening after normal browsing, it’s probably a cookie getting too big or one cookie becoming corrupted. Refreshing the page usually doesn’t help because the issue is with the cookies stored in your browser — not the website itself. Clearing cookies for that specific site usually does the trick, which was a relief once I figured it out.
Fixing the Error in Chrome
If Chrome gives you this cookie-related error, the fix is pretty straightforward — clear out those cookies. You can get straight to Chrome’s cookie settings by typing chrome://settings/cookies into the address bar. It’ll take you directly to “Cookies and other site data,” which is where I finally identified the culprit. Here’s what worked for me:
- Type
chrome://settings/cookiesinto the address bar and press Enter. - In the search box at the top, type the website’s domain — like
example.com— to narrow it down. - Once it appears, click on it to expand and view the cookies stored for that domain.
- Then, hit the trash can icon or click “Remove” to delete those cookies.
This wiped out all cookies related to that site, and after a quick refresh, everything loaded fine. If you want to be thorough, you can also go into the “Clear browsing data” menu (three dots > More tools > Clear browsing data), set the time range to “All time,” tick only “Cookies and other site data,” and click “Clear data.” Just a note — this will log you out of most sites and reset some preferences, so you’ll need to log back in and reconfigure settings.
Manually Clearing Cookies in Chrome
If you prefer a more hands-on approach, you can manage cookies directly:
- Navigate to
chrome://settings/cookies. - Use the search box to find the problematic site, e.g.,
example.com. - Click on the site, then press the trash can icon or “Remove” to delete its cookies.
If that isn’t enough or you’d rather wipe all data for that site, follow this method:
- Open the Chrome menu (three dots at the top right), then go to More tools > Clear browsing data.
- Choose All time for the time range.
- Tick only Cookies and other site data.
- Hit Clear data.
This might log you out from many sites and reset some preferences, but in my case, it finally fixed the error. On my older ASUS device, the cookie storage was buried under Advanced settings, so your experience may vary depending on your browser version.
What About Firefox?
Firefox users, the process is similar, just in a different menu. Head over to Settings > Privacy & Security. Scroll down to “Cookies and Site Data,” then click “Manage Data…”. Enter your site’s domain, like example.com, into the search box, select it from the list, and click “Remove Selected.” Then, click “Save Changes.” It’s basically the same process, just in another spot. Expect to be logged out of that site afterwards, but it’s worth it to fix the 400 error.
Extra Tips & Things to Keep in Mind
One thing I learned — browsers sometimes keep around malformed cookies or ones that got corrupted after crashes or sudden shutdowns. These can cause the same error even after clearing cookies. If that happens, opening developer tools (F12 or Ctrl + Shift + I) and manually deleting site data can help if the usual UI doesn’t work.
Also, remember that deleting cookies may reset your preferences or log you out, so think twice before doing it. If you notice this error popping up on the same few sites regularly, a periodic tidy-up can save a lot of hassle — browsers can get bogged down with bloated cookies over time.
Final Thoughts
Dealing with a “400 Bad Request – Cookie Too Large” error initially felt like a headache, but once I identified that huge cookies were the cause, I realised that clearing them usually solves the issue. Some server configurations are stricter and can make cookies extremely big, making clearing them unavoidable. To prevent this problem recurring, regular cookie management or cleanup can save you from headaches in the long run.
I hope this helps — it took me ages to figure out what was going on, especially with Chrome’s less-than-intuitive cookie storage. Hopefully, this saves someone else a weekend of frustration. Good luck!