A Fatal error like this is showing…. require(): Failed opening required ‘/var/www/vhosts/websitename/wordpress/wp-content/plugins/pluginname/functions_include.php on line 66 etc.
Most content management system such as WordPress, Joomla, Drupal. Or other website building platform including Squarespace, Wix etc require updates for better features, add on’s and security so often not all these updates work well together. In the case with WordPress themes and plugins can clash with each other and cause website errors or even worse your website to crash.