Syntax error on line 11 of /etc/apache2/sites-enabled/gitlab.conf:

/home/git/gitlab# service apache2 restart Syntax error on line 11 of /etc/apache2/sites-enabled/gitlab.conf: Invalid command 'ProxyPreserveHost', perhaps misspelled or defined by a module not included in the server configuration Action 'configtest' failed. The Apache error log may have more information. failed!

/home/git/gitlab# apache2 -v Server version: Apache/2.2.22 (Debian) Server built: Feb 1 2014 21:26:04

Can I comment that line out?