Changed zzz_servicedesk_otobo.conf

<VirtualHost *:80>
# Please change here the otobo admin mail address
ServerAdmin youremail@yourdomain.com


# Please change here the FQDN or hostname, you like to use with OTOBO
ServerName servicedesk.yourdomain.com

# Please change here and add more different FQDN´s or hostnames, you like to use with OTOBO
ServerAlias servicedesk.yourdomain.com


DocumentRoot /opt/otobo/var/httpd/htdocs
HostnameLookups Off
UseCanonicalName Off
ServerSignature Off

Alias /otobo-web/ "/opt/otobo/var/httpd/htdocs/"
ScriptAlias / "/opt/otobo/bin/cgi-bin/"

<IfModule mod_perl.c>

# Setup environment and preload modules
PerlOptions +Parent
Perlrequire /opt/otobo/scripts/apache2-perl-startup.pl

# Reload Perl modules when changed on disk
PerlModule Apache2::Reload
PerlInitHandler Apache2::Reload

# general mod_perl2 options
<Location />
DirectoryIndex index.pl
AddHandler perl-script .pl .cgi
# ErrorDocument 403 /otobo/customer.pl
ErrorDocument 403 /otobo/index.pl
#SetHandler perl-script
PerlResponseHandler ModPerl::Registry
Options +ExecCGI
PerlOptions +ParseHeaders
PerlOptions +SetupEnv