Common HTTP Errors and Troubleshooting Tips

What Is HTTP and How Does It Work?

Hypertext Transfer Protocol (HTTP) is the standard communication protocol used by web browsers and servers to exchange information.

• It appears in URLs as http://, such as in http://www.imp.news.
• HTTP defines how text, images, links, and other content are requested and delivered over the internet.

Similar to protocols like FTP, HTTP allows a client—typically a web browser—to request resources from a remote server.

• These requests typically involve HTML files that are then rendered by the browser.
• While modern browsers still use HTTP, they often hide the prefix in the address bar for simplicity.

History of HTTP

The original HTTP protocol was introduced in the early 1990s by Tim Berners-Lee, the inventor of the World Wide Web.

• It evolved through several key versions, each improving on the last.

Main HTTP versions:

• HTTP 0.9: Supported only basic hypertext documents.
• HTTP 1.0: Introduced features needed for richer websites.
• HTTP 1.1: Addressed performance limitations in HTTP 1.0 and was defined by RFC 2068.
• HTTP 2.0: Approved in 2015, this version includes performance enhancements while maintaining backward compatibility with 1.1.

Standard HTTP is not encrypted, which led to the development of HTTPS, a secure version of HTTP.

• HTTPS uses Secure Sockets Layer (SSL) or Transport Layer Security (TLS) to encrypt traffic, protecting data in transit.

How HTTP Works

HTTP is an application layer protocol that operates over TCP, using a client-server model.

• Web browsers (clients) send requests, and servers respond with the requested resources.
• HTTP uses port 80 by default, though port 8080 is also common.

The main types of HTTP messages include:

• GET: Sends a request with only a URL and optional parameters added to the end.
  • The server processes the request and returns the requested web page or content element.
• POST: Sends data inside the message body, not in the URL, and is used for forms or sensitive data.
• HEAD: Similar to GET, but the server returns only header information, not the full content.

Communication begins when the browser establishes a TCP connection to the server.

• Once the request is complete, HTTP closes the connection, making it a stateless protocol.
• Unlike FTP, which maintains continuous sessions, HTTP treats each request as independent.

Troubleshooting HTTP

HTTP requests can fail due to a variety of reasons, and the protocol is designed to report errors clearly.

• Common causes include user input mistakes, browser issues, server problems, or network interruptions.
• These problems are flagged using HTTP status codes, which help diagnose the issue.

Examples of HTTP error codes:

• 4xx codes: Indicate client-side errors, such as 404 Not Found when a page doesn’t exist.
  • These errors often result from broken links or incorrect URLs.
• 5xx codes: Represent server-side failures, such as internal errors or unavailable services.

Some websites display custom error pages—especially for 404 errors—to improve user experience during navigation failures.