503 critical
503 Service Unavailable
A 503 says the server is temporarily unable to handle the request — usually overload or maintenance. Here’s how to clear it.
What you see
HTTP 503 — Service Unavailable The server is currently unable to handle the request due to temporary overloading or maintenance.
What’s actually happening
Unlike a 500, a 503 is the server saying "I’m alive but can’t serve you right now." It’s meant to be temporary, but a stuck maintenance mode or sustained overload turns it into an outage.
Common causes
- The server is overloaded — too many requests, not enough resources
- A CMS is stuck in maintenance mode (e.g. a WordPress update that died mid-way)
- A plugin or cron job is consuming all available workers
- A DDoS or traffic spike exhausted capacity
How to fix it
- Clear stuck maintenance modeIn WordPress, delete the hidden .maintenance file in the site root via SFTP — a failed update leaves it behind and pins every page at 503.
- Identify what’s eating resourcesCheck CPU/memory and the process list. A runaway plugin, bot crawl, or cron loop is usually the cause. Kill or throttle it.
- Add capacity or cachingIf it’s genuine load, enable full-page caching and/or scale the server. Caching often turns a 503 under load back into a fast 200.
- Rule out the hostOn shared hosting, a noisy neighbor or resource cap can trigger 503s you can’t fix from your side — confirm with your host.
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