Request Header or Cookie Too Large: What It Is + Easy Fixes

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Troubleshoot "request header" on Chrome & other browsers

Co-authored by Rain Kengly Reviewed by Stan Kats

Last Updated: August 23, 2025 Fact Checked

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What does it mean?

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Common Causes

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Troubleshooting

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Video

Are you getting the "Request Header Or Cookie Too Large" error code? You may also see "400 Bad Request" when trying to visit a website. This is a common error, and luckily, it can be fixed by checking a few things on your device. Here's what Request Header Or Cookie Too Large means and how to fix it on Google Chrome, Safari, and more browsers.

Quick Fixes

Clear your browser's cookies and cache.
Reset your browser's settings.
Reduce your file size.
Restart your device.
Flush your DNS cache.
Contact the site owner.

Section 1 of 3:

What does Request Header or Cookie Too Large mean?

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This error code often indicates a loading problem with the website. The 400 Bad Request error may pop up when you try to load a website and your request gets denied by the server. When you try to visit a website, your browser sends data to the website's server. When the size of the data is too large for the server, you'll usually see this error.^{[1]
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- This error can happen due to your own device or the website itself.

Section 2 of 3:

Common Causes

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When you visit a website, files called cookies are created as it saves your browsing data. The cache remembers other parts of the website, such as images. Leaving your cookies and cache alone when you browse the internet can make your frequently visited sites load faster. However, these files can become corrupted over time and cause errors when trying to access the website again.
If you're trying to upload a file onto a website, you may be trying to upload a file that is too large for the server to handle.
Similar to other files, your browser can become corrupted. Whether it breaks from a past update or an outside source, you may have trouble visiting websites until the browser itself gets fixed.
The DNS cache stores records of the domains you have visited. Similar to cookies and cache on your browser, you can clear the DNS cache on your device if the files have become corrupted.
Some site owners may block traffic to their website if it's currently undergoing construction or if they no longer wish to maintain it. In this case, it's entirely up to the site owner if they want to get it back up and running.^{[2]
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Section 3 of 3:

Troubleshooting

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Clear your cookies and cache. This process will vary depending on your device.^{[3]
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- If you're using a desktop or mobile browser:
  - Locate the History menu.
  - Select the option that says something like “Clear browsing history” or “Clear Recent History”.
  - Make sure Cache and cookies or similar options are selected.
  - Set the time range to All, Everything, or similar.
  - Select Clear history.
- If you're using Safari on iOS:
  - Navigate to Settings > Apps.
  - Select Safari.
  - Tap Clear History and Website Data.
  - Select a timeframe and tap Clear History.
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Reset your browser settings. Most browsers have an option in their settings menu to restore the browser’s default settings.
- For example, if you're using Google Chrome, do the following:
  - Click ⋮.
  - Click Settings.
  - Click Reset settings.
  - Click Restore settings to their original defaults.
- If you don't have this option, uninstall your browser, and then download it again.
If you're trying to upload a large file, try compressing it into a ZIP file before you upload it. This will reduce the size substantially. Alternatively, try a different sharing method, such as Google Drive.
Sometimes, a quick restart can fix common issues. Turn off your device fully, wait at least 30 seconds, and then turn it on again.
Make sure your internet connection is strong and stable. If you're using cellular data, you may not have a strong enough connection.
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Flush your DNS cache. Flushing your DNS cache can ensure you have the newest information for the website. This will remove any old and corrupted data.
- If you're using Windows:
  - Open the Start menu and type "command prompt".
  - Right-click Command Prompt and select Run as administrator.
  - Click Yes to confirm.
  - Type ipconfig /flushdns and press Enter.
- If you're using Mac:
  - Open the Terminal.
  - Type sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder and press Enter/Return.
In some cases, you may not be at fault. If the site isn't equipped to handle the traffic or if there's something wrong on their end, you won't be able to successfully load the website. If they aren't available via email or phone, you may be able to find the owner on social media.