Title: Cannot activate plugin Last modified: August 20, 2016 --- # Cannot activate plugin * Resolved [ba0x55](https://wordpress.org/support/users/ba0x55/) * (@ba0x55) * [13 years, 3 months ago](https://wordpress.org/support/topic/cannot-activate-plugin-4/) * Hey, * after upgrading WordPress to 3.5.0 and then 3.5.0 I cannot use this plugin anymore. When I try to activate it the following message from WP is showing up: * Plugin could not be activated because it triggered a fatal error. Fatal error: Class ‘OGraphr_Admin_Core’ not found in /path/to/wordpress/wp-content/plugins/ meta-ographr/meta-ographr_admin.php on line 20 * Before the named version the plugin was usable. * Cheers! * [http://wordpress.org/extend/plugins/meta-ographr/](http://wordpress.org/extend/plugins/meta-ographr/) Viewing 8 replies - 1 through 8 (of 8 total) * Plugin Author [idleberg](https://wordpress.org/support/users/yathosho/) * (@yathosho) * [13 years, 3 months ago](https://wordpress.org/support/topic/cannot-activate-plugin-4/#post-3417326) * i’m assuming you’re using the latest plugin version and do not run wordpress in debug mode? php version? logged in as admin? * Thread Starter [ba0x55](https://wordpress.org/support/users/ba0x55/) * (@ba0x55) * [13 years, 3 months ago](https://wordpress.org/support/topic/cannot-activate-plugin-4/#post-3417352) * Your guess is correct, using the latest version of OGraphr and WP is not running in debug mode. PHP version is 5.3.18 and I am logged in with admin rights. * Plugin Author [idleberg](https://wordpress.org/support/users/yathosho/) * (@yathosho) * [13 years, 3 months ago](https://wordpress.org/support/topic/cannot-activate-plugin-4/#post-3417405) * try a manual install of the plugin and see what happens. i found several class errors on the wordpress support pages and that fixed it most of the time. * > Fatal error in the output generally indicates either your theme doesn’t like > your version of WordPress, you have a plugin that doesn’t like your version > of WordPress, or you have an incomplete install/upgrade. * i tried reproducing the problem on a clean wordpress installation, but to no success. also, i got it running on several other sites that i recently upgraded to the latest wordpress. * hope we can nail this down! * Thread Starter [ba0x55](https://wordpress.org/support/users/ba0x55/) * (@ba0x55) * [13 years, 3 months ago](https://wordpress.org/support/topic/cannot-activate-plugin-4/#post-3417436) * I always do a manual install so this makes no difference. I also set up a new database and instance of WP and tried only this plugin, but no luck. Even in debug mode are no other messages. So I assume that there is a problem with the latest PHP update, hardened settings or something. I am irritaded, because it worked before, no sufficient changes were made and everything else is working. * Plugin Author [idleberg](https://wordpress.org/support/users/yathosho/) * (@yathosho) * [13 years, 3 months ago](https://wordpress.org/support/topic/cannot-activate-plugin-4/#post-3417443) * i can’t install php 5.3.18 on my server, but the plugin runs fine with php 5.3.19. i do get a warning (see below) on the plugin page after activation, but no problems in functionality. * > The plugin generated 260 characters of unexpected output during activation. > If you notice “headers already sent” messages, problems with syndication feeds > or other issues, try deactivating or removing this plugin. * i’m pretty clueless, but i’ll investigate a little. * edit: found the problem for the warning, but it’s probably not related to your problem (you can give it a try though: [http://db.tt/8iZ4J9jE](http://db.tt/8iZ4J9jE)) * Thread Starter [ba0x55](https://wordpress.org/support/users/ba0x55/) * (@ba0x55) * [13 years, 3 months ago](https://wordpress.org/support/topic/cannot-activate-plugin-4/#post-3417445) * Okay, I think I found the bad guy. While tinkering around with this XCache chrashed with a segfault and after this I could activate the plugin with no problem. After restarting the PHP process with loaded XCache I got the error message as above again. So I deactivated XCache and everything is working fine. * Sigh. * Plugin Author [idleberg](https://wordpress.org/support/users/yathosho/) * (@yathosho) * [13 years, 3 months ago](https://wordpress.org/support/topic/cannot-activate-plugin-4/#post-3417446) * i found [this](http://stackoverflow.com/questions/5146387/existing-class-not-found-using-xcache-and-php-5-3-2), but after applying the fix i got the very same error – and i didn’t get it before:/ * Thread Starter [ba0x55](https://wordpress.org/support/users/ba0x55/) * (@ba0x55) * [13 years, 3 months ago](https://wordpress.org/support/topic/cannot-activate-plugin-4/#post-3417447) * For me the fix does not work either. I leave XCache deactivated for the domain using ographr. Maybe one of the next stable versions (on my distro) of PHP/XCache will get me rid of this. Viewing 8 replies - 1 through 8 (of 8 total) The topic ‘Cannot activate plugin’ is closed to new replies. * ![](https://s.w.org/plugins/geopattern-icon/meta-ographr_8a6c7d.svg) * [OGraphr for WordPress](https://wordpress.org/plugins/meta-ographr/) * [Frequently Asked Questions](https://wordpress.org/plugins/meta-ographr/#faq) * [Support Threads](https://wordpress.org/support/plugin/meta-ographr/) * [Active Topics](https://wordpress.org/support/plugin/meta-ographr/active/) * [Unresolved Topics](https://wordpress.org/support/plugin/meta-ographr/unresolved/) * [Reviews](https://wordpress.org/support/plugin/meta-ographr/reviews/) * 8 replies * 2 participants * Last reply from: [ba0x55](https://wordpress.org/support/users/ba0x55/) * Last activity: [13 years, 3 months ago](https://wordpress.org/support/topic/cannot-activate-plugin-4/#post-3417447) * Status: resolved