rails 3 apache Passenger app home page says : We're sorry, but something went wrong

Webrick works fine.

I set up apache and passenger using RVM but when I try to access home page with passenger I get a blank page with this error:
We're sorry, but something went wrong. .
Here's some of my set up:

$ rvmsudo passenger-status
Warning: can not check `/etc/sudoers` for `secure_path`, falling back to call via `/usr/bin/env`, this breaks rules from `/etc/sudoers`. Run:

export rvmsudo_secure_path=1

to avoid the warning, put it in shell initialization file to make it persistent.

In case there is no `secure_path` in `/etc/sudoers`. Run:

export rvmsudo_secure_path=0

to avoid the warning, put it in shell initialization file to make it persistent.
Version : 5.1.11
Date    : 2017-11-20 21:23:15 -0500
Instance: 4f5dvobz (Apache/2.4.18 (Ubuntu) Phusion_Passenger/5.1.11)

----------- General information -----------   
Max pool size : 6
App groups    : 1
Processes     : 1
Requests in top-level queue : 0

----------- Application groups -----------   
/home/deploy/apps/tweetsifter (production):
App root: /home/deploy/apps/tweetsifter
Requests in queue: 0
* PID: 19196   Sessions: 0       Processed: 2       Uptime: 4h 32m 32s
CPU: 0%      Memory  : 606M    Last used: 2m 12s a

passenger version

$ rvmsudo passenger-config --root
Warning: can not check `/etc/sudoers` for `secure_path`, falling back to call via `/usr/bin/env`, this breaks rules from `/etc/sudoers`. Run:

export rvmsudo_secure_path=1

to avoid the warning, put it in shell initialization file to make it persistent.

In case there is no `secure_path` in `/etc/sudoers`. Run:

export rvmsudo_secure_path=0

to avoid the warning, put it in shell initialization file to make it persistent.
/home/deploy/.rvm/gems/ruby-2.0.0-p648/gems/passenger-5.1.11

In the apache error log:

WARNING: potential privilege escalation vulnerability. Passenger is running as root, and part(s) of the passenger root path (/home/deploy/.rvm/gems/ruby-2.0.0-p648/gems/passenger-5.1.11) can be changed by non-root user(s):
The path "/home/deploy/.rvm/gems/ruby-2.0.0-p648/gems/passenger-5.1.11" can be modified by user "deploy" (or applications running as that user). Change the owner of the path to root, or avoid running Passenger as root.

In the error log fileI can see some stdout/printed queries like they show on webrick.
How can I make the home page show/work ?