magento2 – Magento 2 – php fatal error class not found

Whatever I try to run on my SSH-Server it displays the same error:

PHP Fatal error: Uncaught Error: Class ‘MagentoSetupMvcBootstrapInitParamListener’ not found in /var/www/vhosts/
Stack trace:
#0 /var/www/vhosts/ require()
#1 /var/www/vhosts/ MagentoFrameworkConsoleCli->__construct(‘Magento CLI’)
#2 {main}
thrown in /var/www/vhosts/ on line 29

I already tried to check the php files but I am a beginner at php…
Someone knows a solution?