Fix Website "504 Gateway Timeout"

Understanding 504 Gateway Timeout

Nginx/Apache waited too long for a response from the backend (PHP-FPM, database, external API).

Default timeout is often 60 seconds.

Fix 1: Increase PHP Execution Time

In php.ini:

max_execution_time = 300
max_input_time = 300

Or in PHP-FPM pool:

request_terminate_timeout = 300

Restart PHP-FPM.

Fix 2: Increase Nginx Timeouts

Edit site config:

proxy_read_timeout 300s;
proxy_connect_timeout 300s;
proxy_send_timeout 300s;
fastcgi_read_timeout 300s;

Test and reload:

sudo nginx -t
sudo systemctl reload nginx

Fix 3: Optimize Slow Scripts

Identify slow queries/endpoints:

# Enable slow log in PHP
slowlog = /var/log/php-slow.log
request_slowlog_timeout = 5

Check database slow queries:

sudo tail -f /var/log/mysql/mysql-slow.log

Fix 4: Check External API Calls

If your script calls external APIs, implement caching or async processing.

Fix 5: Resource Bottlenecks

top
free -h
iostat -x 1

Upgrade VPS if consistently hitting limits.

Fix 6: For File Uploads

Increase client_max_body_size and timeouts for large uploads:

client_max_body_size 100M;
proxy_read_timeout 600s;