Erro interno do servidor com Nginx e uWSGI

Question

Estou tentando hospedar um aplicativo usando o Nginx no Linode.com, mas estou preso no início da configuração do uWSGI.

Eu usei o guia "Primeiros passos" e "WSGI usando uWSGI e nginx no Ubuntu 12.04 (Precise Pangolin) "guia e eu tenho implantado com sucesso Nginx (tenho Nginx mensagem de boas vindas no navegador).

Embora o tutorial acima seja para o Ubuntu 12.04, usei o 14.04.

O problema começa quando chego à configuração do uWSGI e ao aplicativo 'Hello World' Python. Ir para location / no navegador retorna Failed to load resource: the server responded with a status of 500 (Internal Server Error) e nada é registrado no servidor error.log. location /static funciona e serve arquivos sem problemas.

Eu já experimentei muitas coisas e procurei muito por correção no Google e no Stackoverflow, mas nada, e estou meio que frustrado agora.

Obrigado por qualquer ajuda.

Aqui estão meus arquivos de configuração (eu escondi meu domínio e ip):

/etc/hosts

127.0.0.1   localhost
127.0.1.1   ubuntu
XX.XX.XX.XXX mars

# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

/etc/nginx/sites-enabled/example.com

server {
    listen      80;
    server_name $hostname;
    access_log  /srv/www/example.com/logs/access.log;
    error_log   /srv/www/example.com/logs/error.log;

    location / {
        #uwsgi_pass 127.0.0.1:9001;
        uwsgi_pass  unix:///run/uwsgi/app/example.com/example.com.socket;
        include     uwsgi_params;
        uwsgi_param UWSGI_SCHEME $scheme;
        uwsgi_param SERVER_SOFTWARE nginx/$nginx_version;
    }

    location /static {
        root        /srv/www/example.com/public_html/;
        index       index.html index.htm;
    }

}

/etc/uwsgi/apps-enabled/example.com.xml

<uwsgi>
    <plugin>python</plugin>
    <socket>/run/uwsgi/app/example.com/example.com.socket</socket>
    <pythonpath>/srv/www/example.com/application/</pythonpath>
    <app mountpoint="/">

        <script>wsgi_configuration_module</script>

    </app>
    <master/>
    <processes>4</processes>
    <harakiri>60</harakiri>
    <reload-mercy>8</reload-mercy>
    <cpu-affinity>1</cpu-affinity>
    <stats>/tmp/stats.socket</stats>
    <max-requests>2000</max-requests>
    <limit-as>512</limit-as>
    <reload-on-as>256</reload-on-as>
    <reload-on-rss>192</reload-on-rss>
    <no-orphans/>
    <vacuum/>
</uwsgi>

/srv/www/example.com/application/wsgi_configuration_module.py

import os
import sys
sys.path.append('/srv/www/example.com/application')
os.environ['PYTHON_EGG_CACHE'] = '/srv/www/example.com/.python-egg'

def application(environ, start_response):
    start_response('200 OK', [('Content-Type', 'text/html')])

    return 'Hello world!'

last access log

XX.XX.XX.XXX - - [05/Jul/2015:10:03:37 -0400] "GET / HTTP/1.1" 500 32 "-" "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/43.0.2357.130 Safari/537.36"
XX.XX.XX.XXX - - [05/Jul/2015:10:03:38 -0400] "GET /favicon.ico HTTP/1.1" 500 32 "http://example.com/" "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/43.0.2357.130 Safari/537.36"

only error log I've got only one time when trying to fix this

2015/07/05 08:49:06 [crit] 25301#0: *17 connect() to unix:///run/uwsgi/app/example.com/example.com.socket failed (2: No such file or directory) while connecting to upstream, client: XX.XX.XX.XXX, server: mars, request: "GET / HTTP/1.1", upstream: "uwsgi://unix:///run/uwsgi/app/example.com/example.com.socket:", host: "example.com"
2015/07/05 08:49:07 [crit] 25301#0: *17 connect() to unix:///run/uwsgi/app/example.com/example.com.socket failed (2: No such file or directory) while connecting to upstream, client: XX.XX.XX.XXX, server: mars, request: "GET /favicon.ico HTTP/1.1", upstream: "uwsgi://unix:///run/uwsgi/app/example.com/example.com.socket:", host: "example.com", referrer: "http://example.com/"