What is an “400 bad request” error ?
The HTTP ‘Error 400: Bad Request’ usually appears when a web server receives an unable to understand request. Typically the cause is a malformed syntax. The servers generate the 400 errors, when the request contains syntax not conform to the HTTP protocol.
Why is this happening?
Probably 99% of all cases, this error occurs only on the client side, not the server. Usually this fault of the system installed on the user’s computer. For example the browser, due to corrupted settings, may send invalid requests, and the reason may be in the NET Framework (part of Windows).
How to fix it?
Site owners should know that most likely only they see this error and the other users see the normal site version. So first of all you should check how the website is oppened on another computer. If the problem is seen also on other computers, then you should write to web hosting support as this is that (1%) from cases, when the problem is on the web hosting server.
If we talk about the correction of the browser, you should firstly clear the cache, delete cookies and return the browser settings to “default”. Or try to open the current site in another browser.