Is there anything reported in the error logs?
have you been able to examine the document that was served (if any) in those cases?
i would also check the server access logs on those occasions to determine that there was a normal (200 OK) status code.
Thanks for the responses - no, there is nothing reported in the error logs. Interestingly it seems completely random how it happens and although there are cases where we can't view the source the logs suggest that there was a 200 each time.
We've wondered about memory problems - but don't think that's it.
Likewise, have heard that PHP sometimes causes problems when a process is running. Especially happens in CMS systems.
This is really bizarre - I've got our very friendly hosting company looking at it with their developer techs.
Thanks for your inputs so far!
Does it affect only certain browsers?
There was a recent thread regarding blank pages in IE6 (yes, "recent" & "IE6" !?)... Occasional blank pages in IE6 [webmasterworld.com] - some peculiarity with the Content-Type META tag.
Ha - no, it's not browser dependent and we're not that old school. We've encountered it in Chrome, and Firefox. We don't really use IE and not sure what the developers were using when they encountered the problem either.
We think it's down to processes vying for resources - but how we actually find the cause.. hmmm, I don't know!
Cookies? Cache? Some off the wall thing that you haven't thought about yet? ;)
I get blank pages all the time. But, I browse with cookies off and I chalk it up to my preferences. I have to reload quite a few sites because something in the rendering of the page required cookies and caused something else to choke. I think that is how it works.
do you sometimes cache the html/php output server-side before sending it to the user?
maybe you've got some kind of bug where it's saving a blank page, and then it serves that to the user. no error would show for that, because the error would have occurred beforehand, when you saved the page.
i would check wherever it is you cache your stuff, and see if you've got any 0byte files in there
Thanks for the responses - I'm hoping it's not something we haven't thought of yet, but it is probably something off the wall!
We have eliminated cookies and caching as possibilities - tested thoroughly.
With regards to caching the html / php output server-side, we do have some caching in place, but the randomness of the blank pages (all over the site and even through all the dynamic processes -i.e. search, results, description pages etc etc) seems to suggest it's not that
Will get the guys to look into this more though and post back here.
Any third party calls that may be hanging up? I know, that's such an obvious thing to look at first but I haven't seen it mentioned.
Is it possible that the order of scripts loading may be an issue at times? I've seen unusual things happen at times if the script references in the head are not in proper order.
Is it possible that there is a conflict in the scripts? And that at certain times, depending on how fast the page loads, certain scripts may load out of sequence or something?
Just guessing now based on stuff I've run into during my daily activities online. I've seen lots of issues with third party calls, CDNs, etc. Google included.