Redmine

Hello,

I installed Redmine totally clear on a Test-System.

And since I did that, I've the "Service Unavailable"-Message when I try to connect the page.

Before I installed Redmine:
- uninstalled all Plugins
- rolled back all Patches
- installed all necessary gems

...then I copied the new Redmine-Content excluding configuration.yml & database.yml.
But when I open my page I get the mentioned error.

apache_error.log gets that after every reload:
[Fri Mar 07 11:23:57.252137 2014] [proxy:error] [pid 2680:tid 1692] (OS 10061)Es konnte keine Verbindung hergestellt werden, da der Zielcomputer die Verbindung verweigerte. : AH00957: HTTP: attempt to connect to 127.0.0.1:3002 (127.0.0.1) failed
[Fri Mar 07 11:23:57.252137 2014] [proxy:error] [pid 2680:tid 1692] AH00959: ap_proxy_connect_backend disabling worker for (127.0.0.1) for 60s
[Fri Mar 07 11:23:57.252137 2014] [proxy_http:error] [pid 2680:tid 1692] [client 10.1.100.6:61660] AH01114: HTTP: failed to make connection to backend: 127.0.0.1

Can someone tell me whats wrong?

EDIT:
Should add that the Test-System was 2.4.0
So I wanted to update 2.4.0 --> 2.5.0