A 503 Service Unavailable error means the server is temporarily unable to handle the request. This is usually not caused by PHP code directly, but rather by server-related issues like overload, maintenance mode, or problems with background services (e.g. database or PHP-FPM not responding).
If you're using shared hosting, it may indicate that your site has hit resource limits. On VPS or dedicated servers, check if services like Apache, Nginx, or PHP-FPM are running correctly. Also, some frameworks or CMSs (like Laravel or WordPress) might trigger a 503 during updates or maintenance.
You can often resolve the issue by restarting server services, reviewing logs, or waiting if the server is undergoing routine maintenance. If you're unsure, contact your hosting provider for more details.
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