Invalid command ProxyRequests when setting up jenkins
sudo a2enmod proxy sudo a2enmod proxy_http systemctl restart apache2
If you don't enable proxy_http you get this error in the apache error log file for the site:
AH01144: No protocol handler was valid for the URL / (scheme 'http').If you are using a DSO version of mod_proxy, make sure the proxysubmodules are included in the configuration using LoadModule.