Guide to HTTP 400-499 Errors: Causes and Solutions

HTTP 400-499 errors are a group of HTTP response status codes sent from a server when there is an issue with processing the client's request. Here's a general description of some common errors in this range:


HTTP 400 Bad Request

This error occurs when the server cannot understand or process the client's request due to syntax error, invalid information, or an incomplete request.

HTTP 401 Unauthorized

This error appears when the request requires authentication. The client needs to provide valid login information (e.g., username and password) to access the requested resource.

HTTP 403 Forbidden

This error occurs when the server refuses the client's request without requiring authentication. The reason could be limited access permissions or the resource is not allowed to be accessed.

HTTP 404 Not Found

This is the most common error in this group. It happens when the server cannot find the requested resource (e.g., web page, file) on the server.

HTTP 408 Request Timeout

This error occurs when the client fails to complete the request within the allowed time. This can happen due to unstable network connection or the request processing taking too long.


The errors in the 400-499 range are typically related to client-side issues or misconfiguration on the server.