A 400 error is an HTTP status code displayed by the browser that indicates that the request to load the webpage was incorrect or corrupted and the server couldn’t understand it.
This can occur on any page in any browser. Normally you’d expect a webpage to work correctly, but when this doesn’t happen, you can receive different errors, such as a 400 error.
This means that the request sent to the server, often to load a webpage, was either incorrect or could not be understood. This is often the fault of the user, either through inputting an incorrect URL, or a problem with the user’s device or browser.
For example, it can be due to a cookie on your browser being old or corrupt, out-dated DNS records, or a corrupt version of the webpage you are viewing. Additionally, uploading a very large file to the website, or having a header that is too long can cause the 400 error to display.
However, if you have tried everything, it may be worthwhile contacting the website to see if it is something they need to fix.