Web Browsers - How to Fix a "Bad Request" Error

This document describes what to do if you receive a 400 Bad Request error message upon loading a website.

Problem

When you attempt to access a website, you may sometimes instead receive a "Bad Request" error message where the website content should have loaded. This error often contains the number "400" and may include additional text, such as "Your browser sent a request that this server could not understand. Size of a request header field exceeds server limit."

Solution

First, check the website URL you entered to make sure it is correct. If the web address appears to be entered correctly, then the issue can usually be resolved by clearing your browser's cache and cookies.

Note: Windows users can use CTRL + F5 to bypass the cache and download a website's complete content.

For instructions on performing these steps, click on the appropriate link for the web browser you are using:

Desktop Web Browsers

Clearing the browser cache prevents you from using old/out-of-date versions of websites and protects your personal information. It also helps running some applications better on your computer by freeing up space.

Note: Make sure you set the Time Range to the "All Time" or "Everything" options when available to clear all data. Please save any unpublished work before proceeding; you will be logged out of all sites and applications and will need to re-authenticate.

Table with browser name and links to Windows documents and macOS documents.
Browser	Windows Document Link	macOS Document Link
Google Chrome	Chrome (Windows) - Clearing Cache and Cookies	Chrome (Mac) - Clearing Cache and Cookies
Firefox	Firefox 57+ (Windows) - Clearing Cache and Cookies	Firefox 21+ (Mac) - Clearing Cache and Cookies
Safari	Safari (Windows) - Clearing Cache and Cookies	Safari 10.0.1+ (Mac) - Clearing Cache and Cookies
Opera	Opera (Windows) - Clearing Cache and Cookies	Opera 28.0 (Mac) - Clearing Cache and Cookies
Microsoft Edge	New Edge (Win 10, 8, 7, MacOS) - Clearing Cache and Cookies	New Edge (Win 10, 8, 7, MacOS) - Clearing Cache and Cookies

Mobile Web Browsers

Table with mobile Operating System and corresponding documents on clearing cache and cookies.
Operating System	Document Link
Android	Android 15 (Vanilla Ice Cream) - Clearing Cache and Cookies on Google Chrome
iOS	Safari (iOS) - Clearing Cache and Cookies

Legacy Versions

Windows

Table with browser name and links to Windows documents.
Browser	Document Link
Internet Explorer 9, 10, & 11	Internet Explorer 9, 10, and 11 (Windows) - Clearing Cache and Cookies
Internet Explorer 6	Internet Explorer 6 (Windows) - Clearing Cache and Cookies
Internet Explorer 7	Internet Explorer 7 (Windows) - Clearing Cache and Cookies
Internet Explorer 8	Internet Explorer 8 (Windows) - Clearing Cache and Cookies
Firefox 3.5	Firefox 3.5 (Windows) - Clearing Cache and Cookies

MacOS

Table with browser name and links to macOS documents.
Browser	Document Link
Firefox 3.5 - 20	Firefox 3.5-20 (Mac) - Clearing Cache and Cookies
Opera 10.50	[Link for document 15152 is unavailable at this time]
Safari 5	Safari 5 (Mac) - Clearing Cache and Cookies
Safari 5.1 - 7.9	[Link for document 30233 is unavailable at this time]
Safari 8.0+	Safari 8.0 - 10.0 (Mac) - Clearing Cache and Cookies

Website DNS (Domain Name System) Changes

DNS changes for websites can be cached separately for users on browser and machine. If the website you are trying to access has been moved to a new destination, you may need to flush your local DNS cache in addition to clearing browser cache and cookies before you can receive the updated website destination.

External instructions on how to flush your local DNS cache for Windows, Mac, and Linux can be found here. If you do not have administrative privileges on your machine, restarting the device can also effectively flush your local DNS cache.