This document describes what to do if you receive a 400 Bad Request error message upon loading a website.
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.”
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.
For instructions on performing these steps, download the document from the link above that explains how to do this for the web browser you are using.