Cookies are small pieces of data from websites that are stored on a user’s web browser. They help a website function according to your usage and personalize your activity.
Cache is a quick storage that your web browser refers to when revisiting a website. Instead of downloading the same information every visit, the browser reuses the previous information which reduces traffic and load time.
A 400 Bad Request occurs when a web server doesn’t like your request. Maybe your request doesn’t make sense or you’re asking for too much. The simplest way to fix your request is by starting over (resetting your cache and cookies).
Chrome
Copy and paste this address into the URL search bar: chrome://settings/clearBrowserData
Click the “Advanced” tab
Select All time for the “Time range” drop-down list.
Check the following boxes:
Cookies and other site data
Cached images and files
Click Delete data
Firefox
First click the hamburger menu icon 
Click History
Click Clear recent history…
Select Everything from the “When” drop-down list
Check the following boxes:
Cookies and site data
Temporary cached files and pages
Click Clear
