I encountered this when I recently upgraded to 3.8.1, and then compounded it when I moved the site to dedicated hosting. Previously, all had all operated well. Core upgrades, plugin upgrades, and servers all may contribute individually, or in combination, to this issue.
I’ll offer up some steps I took to identify and eliminate the problem, in the event you wish to perform your own tests.
The white screen of death is often triggered by changes which create php conflicts. Systematically, I completed the following:
– verified and performed any block coding in the theme being used. We’re using a premium theme with modifications & compliant with 3.8.1- but it is possible for a theme to trigger this- as such all scripts were already minified and blocked. But it never hurts to double check this. It’s necessary to eliminate the theme as a conflict. Another way to test the theme (and simpler than what I’ve suggested) is to switch to WP’s 2014 theme and see how it performs. If the problem goes away, it’s the theme. If the problem persists, keep testing. It’s not aesthetically pleasing, but it’s a good step to check.
– turned off all plugins, then turning them all on one-by-one and observing any changes over a few hours. We observed the issue occurring with W3TC.
– Turned off W3TC. Moved the plugin out, and then back, to its folder. Turned it back on. Verified settings were still in tact. Problem persisted. This indicated something in our settings (either with the plugin or on our server was creating a conflict.)
– reinstalled 3.8.1 from the dashboard “updates” option to stabilize any possible core issues. (In fact, anytime our admin slows down, we perform a 3.8.1 reinstall. We have numerous writers for our site.)
– Turned off all caching/ minification options in W3TC. Systematically tested each option by turning each one back on and observing the site’s performance and errors over 48 hours of varying traffic (low vs high traffic spikes.) We identified the culprit for us. It was object caching. When we re-enabled object caching we experienced the white screen of death, as well as 500’s.
– We have all caching turned back on at this time, with the exception of Object Caching. (We’ll trouble shoot this next week.)
– We are okay not using Object Caching for the time being as we’re also using Google PSS for CDN, it’s performing fantastically, Object Caching doesn’t set any of our expiry headers/ headers info, and we’re fully configured in admin and the server for Google PSS. This allows us a little breathing room to resolve the issue with Object caching.
Since different sites use different themes, software (aka plugins), and servers vary in their configurations, there isn’t a one size fits all way to identify and fix the problem with white screens or 500 errors. As such, we have to methodically test our sites. W3TC is a very complex program, too, unlike many plugins.
I hope these ideas for testing, along with your own ideas, can help identify the php conflict for you. Cheers! ??