← All Status Codes
504
Gateway Timeout
🔴 Server Error
Critical Risk
📖 What Is HTTP 504?
The server acting as a gateway did not receive a timely response from the upstream server. The backend is too slow or unresponsive.
🛡️ Security Implications
Slow backend responses can indicate resource exhaustion attacks. Implement query timeouts and circuit breakers.
🔍 Common Causes
Backend processing takes too long, slow database queries, external API timeout, PHP max_execution_time exceeded, large file processing.
🔧 How to Fix
Increase gateway timeout (proxy_read_timeout in Nginx). Optimize slow database queries. Add indexes. Increase PHP max_execution_time. Use async processing.
🖥️ How to Check
curl -I -o /dev/null -w "%{http_code}" https://example.com