Can a Wordpress plugin cause a Squid error?

January 14, 2010 5:34 PM

I'm getting a "Zero Sized Reply" error after migrating my blog to a dedicated server. "Squid did not receive any data for this request," it says. Could a Wordpress plugin cause this? Details and background inside.

After years of headaches with my old hosting provider, and several hackings -- due at least in part to my failure to upgrade to the latest version of WordPress, but in at least one case possibly also a security issue on the provider's end -- I switched to a new provider. I hired a knowledgeable friend to help me disinfect my site first, and we (by which I mean he) migrated everything over to grid service at the new provider. The hackings had made me paranoid, however, and after a month went by without event I decided to upgrade to a dedicated server.

Once again, I hired the friend to help with the move, and he did a great job. He's in a slightly weird position, though, because he normally does everything -- from design to coding to tech -- for his clients, and in my case he's dealing with a pre-existing set-up. I've been blogging since 2002 and been on WordPress all that time, but the tech side of all of this has always been mostly above my head. I know html, and that's about it. But I digress.

He got everything moved to the dedicated server on Tuesday. There was a phpMyAdmin problem initially, but he rebooted the server and everything seemed fine.

Early this afternoon, though, I tried to load my site and got a "Zero Sized Reply" error saying "Squid did not receive any data for this request." Once again he rebooted, and everything was fine, but we put in a support query with the hosting provider, asking whether the problem could be due to having both a grid account (I've put in a close request but it has not yet been processed) and a dedicated server for the same domain. Support says the error is with Squid, and of course that's third party software, so it's up to us to figure out what the problem is.

Does anyone have any idea how Squid might be involved? I don't think core WordPress uses Squid (but please correct me if I'm wrong). Could the error be originating with one of my WordPress Plugins?

I've been trying to research each of them, but not turning up much. In case it helps, here are the plugins I'm using: Akismet, Contact Form 7, Google Analyticator, Sideblog Wordpress Plugin, Twitter Tools, WordPress Exploit Scanner, WP-DBManager, and WPtouch iPhone Theme.

Thanks for any help you're able to offer -- and sorry about my relative cluelessness.

posted by maud to Technology (4 answers total)

Squid is a reverse proxy cache, it's a piece of software that sits between you and a bunch of web servers and caches (holds on to so it can serve quickly for a while) page requests. It's often run on dedicated hosts and isn't the kind of thing most people would ever install, however it is often used by grid computing/large scalability folks.

It sounds like your migration didn't take (dns updates taking a long time?) or there's some other bug. I'd reboot your computer (the one you're browsing on), see if you still get the error, and if you do, get someone else to check and see if the site loads fine for them. If other people are getting the error too, then the question is why your site's spitting out blank pages (usually a php error, check the apache error log) and why squid is sitting in front of your dedicated server (it shouldn't be).

I suppose it's possible that your friend is running squid on the server, though that seems unlikely. If he is, your problem is probably a php or db error and you should check (or have him check) the web server error log.
posted by jeffkramer at 6:07 PM on January 14, 2010

I'd check your server logs on the new machine first. If the requests are reaching it, I'd disable all plugins (& comments too, since antispam will be off).

Squid might be running on your end - your employer or ISP - or on the server. The diagnostic "zero byte" error page should have the name of the server it's running on.
posted by Pronoiac at 6:31 PM on January 14, 2010

Response by poster: This is all really helpful. I forgot to say that I could tell from my stats that no one else was able to reach the site either. There was a 25-minute discontinuation of traffic, apart from a handful of visitors who came in through Google, using cache (probably they were checking to see if the site had been hacked again).
posted by maud at 6:36 PM on January 14, 2010

I'd check the error logs then, or see if you can hit static files (images, css files, robots.txt, the sort of thing you can see through your ftp client). Without knowing what web server you're running it's hard to give specifics, but php also has an option where it'll print those errors to the page instead of return nothing.
posted by jeffkramer at 9:55 PM on January 14, 2010