Fix Chrome Error 400 Bad Request Request Header Or Cookie Too Large (2025)

Updated: 11/29/2025

You try to open a site you use every day, but instead of loading normally Chrome flashes a white page with 400 Bad Request or Request header or cookie too large. Other websites work fine, which makes the problem feel mysterious and frustrating. The truth is that this error usually means your browser is sending an oversized or corrupted cookie header to that specific site, so the server gives up and returns Error 400 until you clean things up.

Table of Contents

Method 1: Clear Site Specific Cookies Instead Of Nuking Everything

Close the tab, open a new one, and type the site address manually into the address bar, then press Enter. The page should now load without Error 400, but you may need to log in again or accept cookie consent banners because the site is seeing you as a fresh visitor.

Method 2: Reset DNS Cache And Check For Proxy Or VPN Conflicts

On Windows press the Windows key, type cmd, right click Command Prompt, and select Run as administrator. Then run the following command to clear the OS DNS cache.

ipconfig /flushdns

Close Command Prompt, reopen Chrome, and test the same site again to see if the 400 Bad Request error disappears.

Warning: Flushing DNS affects all applications on your system, so if you are on a work network with custom DNS rules ask your IT team before changing anything.

Method 3: Remove Corrupted Chrome Profile Data And Reset Settings

If Error 400 still appears only in your main profile, close Chrome completely, then rename the Chrome User Data folder on your system to create a backup, for example add -old to its name. When you reopen Chrome it will generate a new profile from scratch, letting you sign back into your Google account and sync bookmarks without carrying over the corrupted data that caused the Bad Request errors.