Getting a 503 error but the Apache log doesn't seem to give any clues

Question

I'm getting a 503 error whenever I try to request any page. I really don't know how to go about fixing this problem. I've checked the error.log and this is what it contains:

[Fri Jan 13 19:03:41 2012] [notice] caught SIGWINCH, shutting down gracefully
[Fri Jan 13 19:03:51 2012] [notice] Apache/2.2.8 (Ubuntu) PHP/5.2.4-2ubuntu5.17 with     Suhosin-Patch configured -- resuming normal operations
[Fri Jan 13 19:08:59 2012] [notice] caught SIGWINCH, shutting down gracefully
[Fri Jan 13 19:09:41 2012] [notice] Apache/2.2.8 (Ubuntu) PHP/5.2.4-2ubuntu5.17 with Suhosin-Patch configured -- resuming normal operations
[Fri Jan 13 19:11:59 2012] [notice] caught SIGWINCH, shutting down gracefully
[Fri Jan 13 19:12:45 2012] [notice] Apache/2.2.8 (Ubuntu) PHP/5.2.4-2ubuntu5.17 with Suhosin-Patch configured -- resuming normal operations
[Fri Jan 13 19:13:03 2012] [notice] caught SIGWINCH, shutting down gracefully
[Fri Jan 13 19:13:14 2012] [notice] Apache/2.2.8 (Ubuntu) PHP/5.2.4-2ubuntu5.17 with Suhosin-Patch configured -- resuming normal operations
[Sat Jan 14 11:25:28 2012] [notice] caught SIGWINCH, shutting down gracefully
[Sat Jan 14 11:26:10 2012] [notice] Apache/2.2.8 (Ubuntu) PHP/5.2.4-2ubuntu5.17 with Suhosin-Patch configured -- resuming normal operations
[Sat Jan 14 11:34:34 2012] [notice] caught SIGWINCH, shutting down gracefully

I assume this is just reporting that I've rebooted the server from the AWS console.

Answer 1

Phew, fixed! For the benefit of others, the 503 error seems to have been caused by my elastic load balancer not having any healthy instances to route requests to. This was because the URL I'd been using to check for health was throwing some database errors. I simply changed the health check ping target to a path that was working and everything started working again.