Try to remove the mentioned socket file by hand.

Did you download it from our repo or somewhere else? Is repo.ajenti.org/debian/python-psutil_0.6.1-3_amd64.deb installable on your system?

Which architecture do you use?

There's a ZIP link on the github page btw

You can just continue using the old DB, no migrations necessary on this part.

No, you can't "just" migrate stuff from Apache to NGINX. You should first handle the Apache->NGINX config migration, and then add it to Ajenti V.

Could you please run ajenti in foregrond (service ajenti stop; ajenti-panel -v) and reproduce the issue? This should output a traceback in the console.

This is a Gevent bug which prevents SSL working under Python 2.7.9 (in-dev).
I've committed a patch that will fix this problem, and preparing a pull request for gevent devs. In the meanwhile, you can disable SSL, downgrade Python to 2.7.8 or run Ajenti from git source.