Nginx is the preferred reverse proxy server for many websites, and it can efficiently handle a large number of concurrent requests. However, when using Nginx for reverse proxy, it is inevitable to encounter some 404 errors, which brings some troubles to the website access experience. So, how should we deal with 404 errors in Nginx reverse proxy?

I. Understanding how Nginx reverse proxy works

Before we talk about how to handle 404 errors in Nginx reverse proxy, we first need to understand how Nginx reverse proxy works.

Nginx as a high-performance reverse proxy server, it receives the client's request, it will forward the request to the back-end of the real server, and then the server's response back to the client. In this process, Nginx plays the role of a relay, isolates the client from the real server, and plays the role of load balancing and caching.

Second, analyze the reasons for 404 errors

A 404 error, or "page not found" error, indicates that the resource requested by the client does not exist on the server. So, how do 404 errors occur in Nginx reverse proxy?

Usually, 404 errors are due to the fact that the URL requested by the client does not exist on the real server or was misdirected to the wrong address. This can be due to URL misspellings, server-side configuration issues, etc.

Third, to solve the 404 error in the Nginx reverse proxy

With an understanding of why 404 errors occur, let's next explore some ways to resolve 404 errors in Nginx reverse proxy.

1. Check the configuration of the real server

First, we should check the configuration of the real server to make sure that the requested URL exists on the server. You can view the server's configuration information via the command line or configuration file to check if the URL path is correct, if the file exists, etc.

location / {
# Additional configuration information
proxy_pass http://backend_server;
}

In the sample code above, the `proxy_pass` directive forwards the request to the backend server specified by `backend_server`. If configured incorrectly, this will result in a 404 error.

2. Use the try_files directive to resolve 404 errors

Nginx provides the `try_files` directive to try different file paths in a specified order until the corresponding file is found and returned to the client. The `try_files` directive can be added to the `location` block as follows:

location / {
try_files $uri $uri/ /index.php?/$request_uri;
proxy_pass http://backend_server;
}

In the above sample code, the `try_files` directive will try the URI of the request, the URI plus slash, and the path of `index.php?/$request_uri` in turn. If the corresponding file is found, it is returned to the client, otherwise it is passed to the backend server for processing.

3. Use of error pages to handle 404 errors

In addition to using the `try_files` directive, we can also use error pages to handle 404 errors. When Nginx receives a 404 error, the `error_page` directive can be used to specify the path to the error page to be returned.

location / {
# Additional configuration information
proxy_pass http://backend_server;
error_page 404 /404.html.
}

In the above sample code, when Nginx receives a 404 error, it redirects the request to the path `/404.html` and returns it to the client.

From the above discussion, we can conclude the following points to handle 404 errors in Nginx reverse proxy:

1. Check the configuration of the real server to ensure that the URL exists on the server.
2. Use the `try_files` directive to try different file paths to resolve 404 errors.
3. Use error pages to handle 404 errors and improve user experience.

I hope the content of this article can help you better deal with 404 errors in the Nginx reverse proxy to improve the performance of the site and user experience. Using Nginx reverse proxy can not only improve the access speed and reliability of the website, but also better protect the security of the real server. Let's work together to build better Web applications!