Foreman broken! Passenger - Error writing to temporary file

Nobody has touched it but overnight it broke! Now we just get this error from passenger:

Web application could not be started
Error writing to temporary file
Application root
/usr/share/foreman
Environment (value of RAILS_ENV, RACK_ENV, WSGI_ENV and PASSENGER_ENV)
production
Ruby interpreter command
/usr/bin/ruby193-ruby
User and groups
uid=497(foreman) gid=498(foreman) groups=498(foreman),52(puppet)
Environment variables
[cut]

Ulimits

    Unknown

System memory usage

                 total       used       free     shared    buffers     cached
    Mem:         32057      31710        347          3        715      29020
    -/+ buffers/cache:       1973      30084
    Swap:         4047          0       4047

Powered by Phusion Passenger, mod_rails / mod_rack for Apache and Nginx.

I spent nearly all day looking at this but with no avail. Does anyone have any ideas?