Fatal error: call to undefined function is_plugin_active()

• nick

• January 19, 2016 at 4:39 am

I’m seeing the following error after updating to ACF PRO 5.3.3:

PHP Fatal error: Call to undefined function is_plugin_active() in /var/www/example/public_html/example.com/wp-content/plugins/advanced-custom-fields-pro/pro/core/updates.php on line 121

It looks as though advanced-custom-fields-pro/pro/core/updates.php is using is_plugin_active() on line 121, which is an admin-only function.

From line 33 of advanced-custom-fields-pro/pro/acf-pro.php it seems that updates.php will be included outside of the is_admin() conditional, so it’s possible is_plugin_active() may run on the front end:

acf_include('pro/core/updates.php');

The example for is_plugin_active shows how to use it on the front-end if required: https://codex.wordpress.org/Function_Reference/is_plugin_active#Examples

PHP version is 5.5. Host is Netfirms.

• terrence.bogie

• February 27, 2016 at 8:55 am

Getting this too–self-hosted multisite.

• James

• February 28, 2016 at 3:20 pm

Hi @nick and @terrence-bogie

Could one of you open a new ticket here: http://support.advancedcustomfields.com/new-ticket? Please provide the steps to reproduce the issue too.

Thank you very much 🙂

• Elliot

• April 20, 2016 at 8:56 am

Thanks guys.

Adding the following to the top of the function should solve the issue:

// ensure is_plugin_active() exists (not on frontend)
		if( !function_exists('is_plugin_active') ) {
			
			include_once( ABSPATH . 'wp-admin/includes/plugin.php' );
			
		}

Please add this and let me know if it solves the problem for you

Thanks
Elliot

• terrence.bogie

• April 21, 2016 at 1:10 am

I added it like this and so far it seems to have fixed the problem.

		// ensure is_plugin_active() exists (not on frontend)
		if( !function_exists('is_plugin_active') ) {
			
			include_once( ABSPATH . 'wp-admin/includes/plugin.php' );
			
		}		
		
		// bail early if not a plugin (included in theme)
		if( !is_plugin_active($basename) ) {

			return $transient;
			
		}
		

• Elliot

• April 21, 2016 at 9:04 am

Hi @terrence-bogie

That is great news.

I’ll include this in the next version so please keep the code in place for now!

Thanks
Elliot