Redmine

Debian 8

New LAP VServer nothing else than redmine and IspConfig installed.
working (also from web ) with
bundle exec ruby bin/rails server -b my-ip webrick -e production

but not with http://ip/redmine or http/domain.com/redmine

Then I get the error Application error Rails application failed to start properly

but i found nothing with google that solved the problem

At what point can I start to find what is causing the error