Help with PHP Error Causing White Screen in Wordpress

CMS & WordPress
1

Hello. Hope this is the right forum for this question …

We have a wordpress theme called Tyrion which came bundled with revolution slider. At some point we couldn’t activate that plugin anymore without it blowing out the site and giving the white screen treatment. In the WP Engine (host) error log we see many similar errors to the one below:

[Wed Mar 19 22:46:29 2014] [error] [client 50.196.203.102] PHP Fatal error: Uncaught exception ‘Exception’ with message ‘Slider with ID: 1 Not Found’ in /nas/wp/www/cluster-1279/newcourses/wp-content/plugins/revslider/inc_php/framework/functions.class.php:9
Stack trace:
#0 /nas/wp/www/cluster-1279/newcourses/wp-content/plugins/revslider/inc_php/revslider_slider.class.php(78): UniteFunctionsRev::throwError(‘Slider with ID:…’)
#1 /nas/wp/www/cluster-1279/newcourses/wp-content/plugins/revslider/inc_php/revslider_slider.class.php(119): RevSlider->initByID(‘1’)
#2 /nas/wp/www/cluster-1279/newcourses/wp-content/themes/tyrion/theme/functions-theme.php(318): RevSlider->initByMixed(‘1’)
#3 [internal function]: yit_add_slider_class_body(‘’)
#4 /nas/wp/www/cluster-1279/newcourses/wp-includes/plugin.php(429): call_user_func_array(‘yit_add_slider_…’, Array)
#5 /nas/wp/www/cluster-1279/newcourses/wp-includes/general-template.php(1634): do_action(‘wp_head’)
#6 /nas/wp/www/cluster-1279/newcourses/wp-content/themes/tyrion/header.php(54): wp_head()
#7 /nas/wp/www/cluster-1279/newcourses/wp-include in /nas/wp/www/cluster-1279/newcourses/wp-content/plugins/revslider/inc_php/framework/functions.class.php on line 9

It’s as if it doesn’t know where to look for its functions file but usually wordpress puts things in the correct spot automatically so I’m not sure how it would lose track of it’s includes.

I need to get this puppy running again, so any help in knowing what to do about an error like this would be much appreciated.

Right now we have that slider deactivate … but the site URL is http://newcourses.wpengine.com/. However we have another install experiencing a similar problem at http://courses2.wpengine.com/

| scott

2

Hi Scott,

Sometimes WordPress plugins use outdated or poor methods for determining paths. So it is not WordPress that doesn’t know its’ paths it is the plugin and its’ files, but because it is attempted to be loaded by WordPress it breaks the loading when the plugin can’t gracefully exit from a unfound path.

In the root of your WordPress folder in wp-config.php. In this file there is WP-DEBUG which is normally set to false. You can turn this to true and see more of where problems begin and require() type of errors. Be advised that Debug should not be used on a production site as it exposes important details that should normally not be shared.

Once you see the type of errors that are occurring, you can likely better solve this issue. You for example can review the type of path management that is enabled in the slider plugin and think through how it is implementing the path and why it might fail. You can var_dump(); die() in spots of the plugin to get some output to the browser. You may want to var_dump() the path variables or values that are being set in the plugin.

Regards,
Steve

3

Awesome. Thanks ServerStorm for explaining that so well. Debugging is exactly what I need to learn more about. I was wondering if you knew of a few articles I could read or even other forum posts to learn the basics. I know what var_dump() and die() do, but haven’t really applied that to debugging at this point.

Do you use a debugging tool or just the two functions mentioned?

| scott

4

Hi Scott,

I don’t know of any debugging articled because I’ve done this long enough to know what to do; I have see chapters in WordPress plugin books.

There is a good php debugger called XDebug. There are good articles online about it. If you use an editor such as Sublime it supports XDebug: only some editors due.

A debugger like this, allows you to step through your code and see the path of execution and object, array, and variable values.

I work on a Linux OS so I use eclipse as my IDE and it also supports XDebug.

Regards,
Steve