Just come across an issue with a site running 2.2.1 whereby the site returns a ERR_EMPTY_RESPONSE when loading the site and the control panel.
I have tracked the issue down to the security code used to restrict the Freelancer license. It appears (to me) as though the code is attempting to access an undeclared variable and causing the site to bail out during the template parsing process.
I solved the issue by commenting out two separate instances of the security code and the site now works fine. I appreciate that the site is not running the latest version, but the same code is present in both versions.
I wanted to know if this is a known issue or if not make you aware of it. Rather than paste the filenames and locations of the security code in public forums, if you contact me directly at chris <at> moresoda.co.uk I would be happy to provide you with the code locations that were causing the issue.