Title: Can’t activate plugin
Last modified: March 16, 2018

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# Can’t activate plugin

 *  Resolved [cdevine](https://wordpress.org/support/users/cdevine/)
 * (@cdevine)
 * [8 years, 2 months ago](https://wordpress.org/support/topic/cant-activate-plugin-79/)
 * When I try to activate the plugin, I get this error:
 * Warning: session_start(): user session functions not defined in wp-content/plugins/
   custom-sidebars/inc/external/wpmu-lib/inc/class-thelib.php on line 145 Fatal 
   error: session_start(): Failed to initialize storage module: user (path: ) in
   wp-content/plugins/custom-sidebars/inc/external/wpmu-lib/inc/class-thelib.php
   on line 145
 * Running PHP 7.0 and the WordPress 4.9.4

Viewing 4 replies - 1 through 4 (of 4 total)

 *  Thread Starter [cdevine](https://wordpress.org/support/users/cdevine/)
 * (@cdevine)
 * [8 years, 2 months ago](https://wordpress.org/support/topic/cant-activate-plugin-79/#post-10083537)
 * Updated to PHP 7.2 and the plugin activated.
 *  [Dimitris – WPMU DEV Support](https://wordpress.org/support/users/wpmudev-support6/)
 * (@wpmudev-support6)
 * [8 years, 2 months ago](https://wordpress.org/support/topic/cant-activate-plugin-79/#post-10083562)
 * Hello there [@cdevine](https://wordpress.org/support/users/cdevine/),
 * hope you’re doing good today! 🙂
 * I’ve just tried to replicate this in a fresh WP installation, running PHP 7.0.28,
   but plugin activated without any issues.
 * This may be a plugin or theme conflict. Please attempt to disable all plugins,
   and use one of the default (Twenty*) themes. If the problem goes away, enable
   them one by one to identify the source of your troubles.
 * If you can install plugins, install “Health Check”: [https://wordpress.org/plugins/health-check/](https://wordpress.org/plugins/health-check/)
   
   On the troubleshooting tab, you can click the button to disable all plugins and
   change the theme for you, while you’re still logged in, **without affecting normal
   visitors to your site**.
 * Let us know, if that made any difference and if you were able to locate any other
   plugin or theme causing that.
 * Warm regards,
    Dimitris
 *  [Dimitris – WPMU DEV Support](https://wordpress.org/support/users/wpmudev-support6/)
 * (@wpmudev-support6)
 * [8 years, 2 months ago](https://wordpress.org/support/topic/cant-activate-plugin-79/#post-10083675)
 * Hello there [@cdevine](https://wordpress.org/support/users/cdevine/),
 * it seems that we cross-posted and hadn’t seen that it worked for you.
    Appreciate
   the feedback here! 🙂
 * Would this PHP update work for you?
    Please advise!
 * Take care,
    Dimitris
 *  Thread Starter [cdevine](https://wordpress.org/support/users/cdevine/)
 * (@cdevine)
 * [8 years, 2 months ago](https://wordpress.org/support/topic/cant-activate-plugin-79/#post-10083711)
 * It’s working now. Thanks for the quick response.

Viewing 4 replies - 1 through 4 (of 4 total)

The topic ‘Can’t activate plugin’ is closed to new replies.

 * ![](https://ps.w.org/custom-sidebars/assets/icon-256x256.png?rev=1414065)
 * [Custom Sidebars - Dynamic Sidebar Classic Widget Area Manager](https://wordpress.org/plugins/custom-sidebars/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/custom-sidebars/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/custom-sidebars/)
 * [Active Topics](https://wordpress.org/support/plugin/custom-sidebars/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/custom-sidebars/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/custom-sidebars/reviews/)

 * 4 replies
 * 2 participants
 * Last reply from: [cdevine](https://wordpress.org/support/users/cdevine/)
 * Last activity: [8 years, 2 months ago](https://wordpress.org/support/topic/cant-activate-plugin-79/#post-10083711)
 * Status: resolved