Website killed: Failed opening required ‘class.pope_cache.php’

Hello Team,

I’m still running PHP 5.6 on Debian 8 as it’s still supported by my distribution and after updating to WordPress 5.4 it seems that Nextgen gallery plugin killed my website – I cannot load it or access the web admin. I turned on the debug mode in wp-config.php and it showed the following:

Warning: require_once(): open_basedir restriction in effect. File(/var/www/clients/client9/web19/web/wp-content/plugins/nextgen-gallery/vendor/reactr-io/pope-framework/lib/class.pope_cache.php) is not within the allowed path(s): (/var/www/clients/client9/web17/web:/var/www/clients/client9/web17/private:/var/www/clients/client9/web17/tmp:/var/www/example.com/web:/srv/www/example.com/web:/usr/share/php5:/usr/share/php:/tmp:/usr/share/phpmyadmin:/etc/phpmyadmin:/var/lib/phpmyadmin) in /var/www/clients/client9/web19/web/wp-content/plugins/nextgen-gallery/vendor/reactr-io/pope-framework/lib/autoload.php on line 5

Warning: require_once(/var/www/clients/client9/web19/web/wp-content/plugins/nextgen-gallery/vendor/reactr-io/pope-framework/lib/class.pope_cache.php): failed to open stream: Operation not permitted in /var/www/clients/client9/web19/web/wp-content/plugins/nextgen-gallery/vendor/reactr-io/pope-framework/lib/autoload.php on line 5

Fatal error: require_once(): Failed opening required 'class.pope_cache.php' (include_path='.:/usr/share/php:/usr/share/pear') in /var/www/clients/client9/web19/web/wp-content/plugins/nextgen-gallery/vendor/reactr-io/pope-framework/lib/autoload.php on line 5

Disabling your plugin via FTP solved the issue but the web is missing the gallery :).

The contents of the file /plugins/nextgen-gallery/vendor/reactr-io/pope-framework/lib/autoload.php

is following:

<?php

if (!defined('POPE_VERSION')) {
	define('POPE_VERSION', '0.14');
	require_once('class.pope_cache.php');
	require_once('class.extensibleobject.php');
	require_once('interface.component.php');
	require_once('class.component.php');
	require_once('interface.component_factory.php');
	require_once('class.component_factory.php');
	require_once('class.component_registry.php');
	require_once('interface.pope_module.php');
	require_once('class.base_module.php');
	require_once('class.base_product.php');
}

Any help is appreciated.

Thank you.