http 400 BAD REQUEST
The server cannot or will not process the request due to something that is perceived to be a client error (e.g., malformed request syntax, invalid request message framing, or deceptive request routing).
The 400 Bad Request error is an HTTP status code that means that the request you sent to the website server, often something simple like a request to load a web page, was somehow incorrect or corrupted and the server couldn’t understand it.
Let’s Understand 400 Request
The 400 Bad Request error is often caused by entering or pasting the wrong URL in the address window but there are some other relatively common causes as well.
400 Bad Request errors appear differently on different websites, so you may see something from the short list below instead of just “400” or another simple variant like that:
400 Bad Request
Bad Request. Your browser sent a request that this server could not understand.
Bad Request – Invalid URL
HTTP Error 400 – Bad Request
Bad Request: Error 400
HTTP Error 400. The request hostname is invalid.
400 – Bad request. The request could not be understood by the server due to malformed syntax.
The client should not repeat the request without modifications.
What is Error 400
The Web server (running the Web site) thinks that the data stream sent by the client (e.g. your Web browser or our CheckUpDown robot) was ‘malformed’ i.e. did not respect the HTTP protocol completely. So the Web server was unable to understand the request and process it.
It almost always means bad programming of the client system and/or the Web server.
How to Fix the 400 Bad Request Error
- Check for errors in the URL. The most common reason for a 400 Bad Request error is because the URL was typed wrong or the link that was clicked on points to a malformed URL with a specific kind of mistake in it, like a syntax problem.
- Important: This is most likely the problem if you get a 400 Bad Request error. Specifically, check for extra, typically non-allowed, characters in the URL like a percentage character. While there are perfectly valid uses for something like a % character, you won’t often find one in a standard URL.
- Clear your browser’s cookies, especially if you’re getting a Bad Request error with a Google service. Many sites report a 400 error when a cookie it’s reading is corrupt or too old.
- Clear your DNS cache, which should fix the 400 Bad Request error if it’s being caused by outdated DNS records that your computer is storing. Do this in Windows by executing ipconfig /flushdns from a Command Prompt window.
- Important: This is not the same as clearing your browser’s cache.
- Clear your browser’s cache. A cached but corrupt copy of the web page you’re trying to access could be the root of the problem that’s displaying the 400 error. Clearing your cache is unlikely the fix for the majority of 400 bad request issues, but it’s quick and easy and worth trying.
- If you’re uploading a file to the website when you see the error, chances are the 400 Bad Request error is due to the file being too large, and so the server rejects it.
- In some relatively rare situations, two servers may take too long to communicate (a gateway timeout issue) but will incorrectly, or at least unhelpfully, report the problem to you as a 400 Bad Request.
- While this is not a common fix, try troubleshooting the problem as a 504 Gateway Timeout issue instead, even though the problem is being reported as a 400 Bad Request.
- If the 400 error is happening on nearly every website you visit, the problem most likely lies with your computer or internet connection. Run an internet speed test and check it with your ISP to make sure everything is configured correctly.
- Contact the website directly that hosts the page. It’s possible that the 400 Bad Request error actually isn’t anything wrong on your end but is instead something they need to fix, in which case letting them know about it would be very helpful.
- If nothing above has worked, and you’re sure the problem isn’t with your computer, you’re left with just checking back later.