What does HTTP error 503 mean?
Posted: Tue Dec 27, 2011 11:47 am
If you receive this error when attempting to view one of your pages, typically this means that you are exceeding the number of concurrent page loads allowed by your chosen webhosting plan. It's difficult to do this under normal usage of even a busy site because each request's runtime should be very short (allowing far more per second than the number allowed at a time by the plan), so usually one of two problems is occurring:
- You have a script that is causing a commonly-accessed page to take a long time to load. For instance, if you make use of the free Coral CDN, and it matches your client up with a slow node, this might occur. Or, your script might depend on the result of a remote service that might be down and timing out (such as a game server, if it queries the server directly). Or, there might be a bug in the script that just causes it to use significant CPU resources.
Troubleshooting this possibility usually involves loading your page with a browser plugin such as Firebug running to identify which component is loading slowly, then proceeding with debugging of the actual script, if necessary.
- Your site is under attack.