An Error Code 400 (Bad Request) is perceived by the server as a generic client error and it is returned when the server determines the error doesn’t fall in any of the other status code categories.

The key concept to understand here is that the Error Code 400 (Bad Request) error is something that has to do with the submitted request from the client before it is even processed by our server.

While there are many causes for an Error Code 400 error, the most common one that is experienced by our students occurs when their web browser's cache or stored cookie becomes corrupted. This will result in the connection being refused and a 400 Bad Request error is triggered.

When this error occurred, you will get a web page that looks like this if using the Chrome or Edge Browsers:

If you are using Firefox or Safari, this will often result in a blank page, like this:

How to Clear Your Browser's Cache

If any locally stored website files have been corrupted this can cause a 400 Bad Request error to be returned instead of the expected website content.

This includes all types of files a website needs to properly run such as:

  • HTML
  • JavaScript
  • Text/config files
  • CSS
  • Media (images, videos, audio)
  • Data files (XML, JSON)

These files are stored locally on your computer by the browser when the website is originally visited.

To fix this, the browser cache needs to be cleared.

In Chrome, click on the three-dotted icon on the right-hand corner and select the More Tools > Clear Browsing Data from the popup menu.

Clearing the browser cache menu option

Clearing the browser cache menu option

This will display the Clear browsing data window. In here, you’ll want to make sure the Cached images and files option is checked and then click on the Clear data button to clear the browser cache.

You can also choose to delete recent files for a specific time range via the Time range dropdown. However, to make sure all potentially corrupted files are removed we recommend deleting all locally stored files by selecting the All time option.

Clear browsing data options

Clear browsing data options

If you’re using an alternative browser, check this guide for clearing the browser cache for all the major browsers (Mozilla Firefox, Safari, Internet Explorer, Microsoft Edge, Opera).

How to Clear Your Browser's Cookies

If clearing your browser cache didn’t work, then it’s time to delete the cookies too. A single website can use dozens of different cookies. If just one of them is expired or becomes corrupted, then it can be enough to trigger a 400 Bad Request.

To clear your cookies in Chrome, open up the Clear browsing data window by clicking the icon with the three dots in the top-right corner and select More Tools > Clear Browsing Data from the popup menu.

Make sure the Cookies and other site data is checked and select All time for the date range option to delete all current website cookies.

Clear browsing data options (cookies)

Clear browsing data options (cookies)

Once done, try loading the website which returned the 400 Bad Request error again. Assuming the site uses cookies, clearing them out from your browser could fix the issue as it’s often associated with corrupt or expired cookies.

To clear cookies in browsers other than Chrome please read this guide here.

What can I do if that doesn't work?

If clearing your cache and browser's cookies does not resolve the issue, please email for further assistance.