How to Fix 504 Gateway Timeout Error in Nginx with PHP-FPM (Quickly)

✨ Quick Answer

The 504 Gateway Timeout error in an Nginx and PHP-FPM web server stack indicates that Nginx, operating as a reverse proxy gateway, did not receive a timely response from the upstream PHP-FPM worker process before the configured timeout interval expired.

Quick Diagnostics

Cause

PHP script execution time exceeds Nginx fastcgi_read_timeout boundary

Solution

Increase fastcgi_read_timeout 300s; in Nginx server block configuration

Cause

Low max_execution_time and request_terminate_timeout in php.ini and PHP-FPM pool

Solution

Raise max_execution_time = 300 in php.ini and request_terminate_timeout = 300s in www.conf

The 504 Gateway Timeout error in an Nginx and PHP-FPM web server stack indicates that Nginx, operating as a reverse proxy gateway, did not receive a timely response from the upstream PHP-FPM worker process before the configured timeout interval expired.

Step-by-Step Solution

1. 1

   Step 1: Increase Timeout Directives in Nginx Configuration

   Open your site virtual host configuration file (e.g., /etc/nginx/sites-available/mysite.conf):

   NGINX Copy

   server {
       listen 80;
       server_name mysite.com;
       root /var/www/mysite;
   
       location ~ \.php$ {
           include snippets/fastcgi-php.conf;
           fastcgi_pass unix:/var/run/php/php8.3-fpm.sock;
   
           # Increase upstream FastCGI timeout limits to 300s
           fastcgi_connect_timeout 300s;
           fastcgi_send_timeout 300s;
           fastcgi_read_timeout 300s;
           
           # Buffer optimization for large payload transfers
           fastcgi_buffer_size 128k;
           fastcgi_buffers 4 256k;
           fastcgi_busy_buffers_size 256k;
       }
   }
   

2. 2

   Step 2: Configure Execution Boundaries in php.ini

   Update execution and memory settings inside /etc/php/8.3/fpm/php.ini:

   INI Copy

   ; Maximum execution time in seconds
   max_execution_time = 300
   
   ; Maximum input parse time
   max_input_time = 300
   
   ; Memory limit for heavy data operations
   memory_limit = 512M
   

3. 3

   Step 3: Tune PHP-FPM Worker Pool (www.conf)

   Edit your active PHP-FPM worker pool configuration file (/etc/php/8.3/fpm/pool.d/www.conf):

   INI Copy

   ; Terminate long-running worker requests after 300 seconds
   request_terminate_timeout = 300s
   
   ; Ensure adequate worker availability under concurrent load
   pm = dynamic
   pm.max_children = 50
   pm.start_servers = 10
   pm.min_spare_servers = 5
   pm.max_spare_servers = 20
   

4. 4

   Step 4: Test Syntax and Restart Services

   Confirm configuration integrity prior to restarting server daemons:

   BASH Copy

   # 1. Test Nginx syntax
   sudo nginx -t
   
   # 2. Restart PHP-FPM and Nginx daemons
   sudo systemctl restart php8.3-fpm
   sudo systemctl restart nginx
   

❓ Frequently Asked Questions (FAQ)

What is the difference between 502 Bad Gateway and 504 Gateway Timeout?

A 502 error means PHP-FPM crashed or the socket is unreachable immediately. A 504 error means PHP-FPM is alive, but the worker process took too long to complete the request.

Does Cloudflare have its own 504 timeout limit?

Yes. Cloudflare imposes a hard 100-second timeout on Free and Pro tiers. If your backend takes longer than 100 seconds, Cloudflare will return a branded 504 page.