HTTP 400 Bad Request

In short: The server does not understand the request because it is malformed.

In more detail: From the server’s point of view the error lies with the client.

In Depth

Possible causes

• Invalid URL, broken parameters, cookie too long.
• Malformed JSON in the request body of an API.
• Headers too large.

Solutions

1. Check the URL for special characters.
2. Delete the site’s cookies.
3. For APIs check the request and format (JSON) and read validation errors.

See also: HTTP, JSON, API