503 Service Temporarily Unavailable Causes

Server overload: Service is temporarily unable to handle requests.

Check Server Status

cPanel → Metrics → Service Status → Look for red indicators on Apache, PHP-FPM, or MySQL.

Resource Spike

Resource Usage → Check for CPU, RAM, or entry process spikes.

Immediate Fixes

Restart Services (Host Level)

Contact host to restart Apache or PHP-FPM.

Kill Hung Processes

CPU and Concurrent Connection Usage → Kill long-running processes.

Enable Aggressive Caching

LiteSpeed Cache or Redis to reduce server load.

Prevention Table

CausePrevention
Traffic spikeEnable full-page caching
Bad scriptOptimize or disable
Resource limitUpgrade hosting plan