Common HTTP 4xx status codes and error analysis

To understand the meaning of 4xx status codes and common errors in the HTTP protocol, specific code examples are needed

HTTP protocol is the basic protocol for Internet communication. It defines the client and Communication specifications between servers. When communicating using the HTTP protocol, the client sends a request and the server returns a response. The HTTP status code is a mechanism used by the server to indicate the result of request processing.

The HTTP status code consists of three digits to facilitate the classification of different status categories. Among them, the 4xx status code indicates that the request sent by the client has an error and the server cannot process it.

Let’s learn about some common 4xx status codes, their corresponding meanings and common errors.

1. 400 Bad Request: The request sent by the client has a syntax error.
   In the following example, we sent an invalid POST request to the server, which was missing necessary parameters:

import requests

url = 'http://example.com/api/create'
data = {
    'name': 'John'
}

response = requests.post(url, data=data)
print(response.status_code)

2. 401 Unauthorized: The request requires user authentication.
   In the following example, we sent a GET request to the server that required user authentication, but did not provide the correct credentials:

import requests

url = 'http://example.com/api/users/1'

response = requests.get(url, auth=('username', 'password'))
print(response.status_code)

3. 403 Forbidden: The server refused to execute the client end request.
   In the following example, we try to send a request to the server for a resource that we do not have permission to access:

import requests

url = 'http://example.com/api/admin/users'

response = requests.get(url)
print(response.status_code)

4. 404 Not Found: The server cannot find the requested resource.
   In the following example, we requested a page that does not exist from the server:

import requests

url = 'http://example.com/nonexistent-page'

response = requests.get(url)
print(response.status_code)

5. 405 Method Not Allowed: The request method is not allowed by the server.
   In the following example, we sent a request method that is not allowed to the server:

import requests

url = 'http://example.com/api/create'

response = requests.delete(url)
print(response.status_code)

6. 408 Request Timeout: The server timed out while waiting for the client to send the request.
   In the following example, our request failed to be sent to the server within the specified time:

import requests

url = 'http://example.com/api/create'

response = requests.get(url, timeout=1)
print(response.status_code)

The above are some common 4xx status codes and their meanings. When we write web applications or use web services, it is very important to understand these status codes and their meanings. Accurately handling these error status codes when processing HTTP requests can improve application reliability and user experience.

When we capture the 4xx status code, we can perform corresponding processing, such as outputting error information, retrying the request, or jumping to the error page, etc. This depends on the specific application and business logic requirements.

Finally, we need to note that although the 4xx status code is a client error, sometimes it may also be caused by a server-side problem. Therefore, when debugging and solving problems, possible errors on the server side should also be taken into consideration.

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