NGINX Error 413: Request Entity Too Large – Causes and Solutions

Understanding NGINX Error 413

Error 413 ‘Request Entity Too Large’ in NGINX occurs when a client request exceeds the size limit that a server is willing to process. This is often encountered in environments where users are uploading files or submitting data forms that exceed the default configured limits in NGINX.

Solutions to Resolve NGINX Error 413

Increase client_max_body_size

By default, NGINX has a limit of 1MB for upload size. You can increase this value to allow larger file uploads.

1. Open your NGINX configuration file (nginx.conf) usually located in ‘/etc/nginx/’ or ‘/etc/nginx/sites-available/’.
2. Add or edit the client_max_body_size directive in the HTTP, server, or location context to a value that suits your needs, like 50M for 50 megabytes.
3. Reload NGINX to apply the changes using sudo nginx -s reload.

<http> client_max_body_size 50M; </http>

Note: Increasing client_max_body_size may allow your server to accept larger uploads, but keep in mind server capacity and resource constraints, as this could potentially lead to resource exhaustion with too many large uploads.

Check and Increase the value of client_body_buffer_size

If the uploaded data is larger than the buffer size, then NGINX will write a part of it to a temporary file. Increasing this buffer might prevent NGINX from writing to a temporary file for the requests smaller than the specified buffer size.

1. Again, edit the NGINX configuration file.
2. Set the client_body_buffer_size directive to a higher value, depending on your requirements.
3. Restart NGINX to make the buffer size change effective.

Example:

http {
    client_body_buffer_size 128k;
}

Note: This setting can reduce disk I/O for large, but not too large, requests. Keep a balance as too large buffer sizes can occupy more memory.

Adjusting the client_body_timeout

Modify how long NGINX will wait for the client to send the entire request body. Increasing this timeout is useful if users with slow connections are experiencing issues.

1. Edit the NGINX configuration file where the timeouts are set.
2. Change the value of client_body_timeout to an appropriate duration.
3. Reload or restart NGINX for the changes to be effective.

Example:

http {
    client_body_timeout 120s;
}

Note: Increasing timeout duration can help users with slow connections, however, keep in mind that this could also allow a client to hold a connection longer, potentially leading to a denial of service if too many long-duration connections are held open.

Configure Temporary File Path

If the upload process is running into filesystem permissions or path issues, configuring the proper path may resolve the 413 error.

1. Set the client_body_temp_path in the NGINX config file to a directory with the appropriate permissions.
2. Ensure the NGINX user has permissions to write to this directory.
3. Reload NGINX to engage the new temporary file path settings.

Example:

http {
    client_body_temp_path /var/nginx/tmp;
}

Note: Without the proper permissions, NGINX cannot write temporary files, which can cause an Error 413. Ensure the directory specified exists and has enough space to handle the temporary files.

Conclusion

In conclusion, the NGINX Error 413 ‘Request Entity Too Large’ is typically due to configuration limits set to prevent excessive resource usage. It’s important not to increase the limits without considering the available server resources and potential security issues. Apply changes cautiously to find the right balance between functionality and system stability.