Custom Apache 404 page

I found the answer myself.

You have to edit the file /etc/apache2/conf.d/localized-error-pages

sudoedit /etc/apache2/conf.d/localized-error-pages

You can enter plaintext or link to a script or html

<VirtualHost 192.168.0.1:80>
    ServerAdmin [email protected]
    ServerName host.ru
    ServerAlias www.host.ru
    DocumentRoot /home/WebServer/www/host.ru/public_html/
    ErrorLog /home/WebServer/www/host.ru/logs/error.log
    CustomLog /home/WebServer/www/hostu/logs/access.log combined


    Alias /error_html/ "/home/WebServer/www/host/error_html/"
    <Directory "/home/WebServer/www/host.ru/error_html">
        AllowOverride None
        Options IncludesNoExec
        AddOutputFilter Includes html
        AddHandler type-map var
        Order allow,deny
        Allow from all
        LanguagePriority en cs de es fr it nl sv pt-br ro
        ForceLanguagePriority Prefer Fallback
    </Directory>
    ErrorDocument 404 /error_html/HTTP_NOT_FOUND.html
</VirtualHost>