I have began obtaining a really strange error on the server of mine and I have no clue how you can repair it. The fundamental setup is really a Wordpress (not v3, the prior stable release) site on PHP-FPM + APC on nginx on Ubuntu Lucid.

For five approximately minutes at any given time, some pages will just return straight out, blank page, no content. I'll watch for a little, repeat the process and will also work fine.

It's only been happening within the last week approximately but there has not really been any alternation in code, platform or quantity of customers.

I am banging my mind against a wall trying to puzzle out how it may be happening... I am available to all suggestions so that as ever, if you want extra detail, just drop a comment and I'll jump on it As soon as possible.

I've got a varnish proxy before my wordpress installation. A error which happened some month ago: wordpress transfers many information within the request header and also the header size was limited on the old version of varnish. Maybe such like with nginx. But it's really a wild guess.

As Artefacto stated: Look into the log.

I'm not sure the precise answer, but look at your error confirming along with your logs files. For those who have error confirming switched entirely off, you might be missing something critical that blocks page execution. Also, if Apache or PHP segfaults, it sometimes will return blank content - you need to observe that inside your log files.

An indicator is always to look for OOM (from memory). This is often difficult to place sometimes because PHP usually runs for one couple of seconds.

Take a look at APC, it is also recognized to segfaults (see google), try without them.

If you're drained of memory, try growing the memory for Wordpress by putting this line presents itself your wordpress-config.php file:

define('WP_MEMORY_LIMIT', '64M');

or perhaps in your php.ini, if you can get it:

memory_limit = 64M;