HTTP Status code 400

Status code 400 represents a client or user side HTTP error. Whenever an invalid request is sent to the server by the user then the server reports it directly and generates 400 status error in return.

Common reasons of status code 400 may include the following:

• URL Syntax Error - The most common reason for the HTTP error 400 is an incorrectly typed URL (Uniform Resource Locator), or a deformed syntax(bad), or a URL that contains some illegal characters. It might happen mistakenly by the user due to typing errors or sometimes it happens if URL encoding has been done incorrectly. 
• Corrupted Browser Cache & Cookies - Apart from URL syntax error, the server might trigger the 400 bad error because it may detect the presence of some corrupted files in the browser cache memory or other reasons may include expired or damaged cookies. The user might also encounter a 400 Bad Request error if he/she tries to gain access to their admin area after some time of their last log-in session, because the process following which the cookie was managing the login authentication information may have gotten expired, and it cannot further authenticate the same valid user with admin rights which eventually results in the connection being declined.
• DNS Lookup Cache - 400 Bad Request also occurs if the local Domain name server data stored is not in sync with the registered DNS data.
• File Size Exceeds Limit - If the files uploaded by user on the website are too heavy for the upload request to be satisfied, 400 status error code triggers. It is strictly associated with the server's file size limit and changes based on its setup.
• Generic Server Error - The 400 bad request error also occurs if there are any technical issues on the server-side. It might represent a generic problem with server, server or network glitch, or any other undefined volatile issues.

Different ways to fix the bad 400 errors are as follows:

• Verify the Submitted URL
• Clear Browser Cache
• Clear Browser Cookies
• File Upload should not exceed Server Limit
• Clear DNS Cache
• E-activate Browser Extensions