Apache Web server logging extra “500” errors (fixed)

Our Web hosting customers who use FastCGI have been seeing extra “500 internal server” errors in their logs and statistics since September 12.

The good news is that this is just a logging bug caused by a recent Apache Web server update. Visitors to your site are seeing exactly what they always saw, and there isn’t any problem besides the incorrect logging.

The bug happens when a computer connects to your site and successfully requests a page, but closes the connection before the entire page is received.

That situation happens fairly often with Mozilla browser “prefetching”, for instance. It’s especially common on WordPress blogs because they contain prefetching hints.

Previous version of Apache would log these broken connections as a successful “200” status code, albeit with a smaller-than-normal size. That makes sense: there’s no problem on the server end. But this Apache bug fix causes an interrupted connection to send a much quicker notice to the FastCGI Apache module. That module logs the unfinished page as a 500 error, even though there’s nothing happening that hasn’t aways happened.

We plan to patch the FastCGI module to prevent it from changing the logging, which will fix this annoyance. We’ll post an update as soon as this change has been made.

Update September 18: This issue has been fixed on all our servers as of 1:10 PM Pacific time.