Nginx выдает ошибку 404 при попытке доступа к контроллеру CodeIgniter (PHP)

Я пытаюсь использовать CodeIgniter с Nginx. Я в разработке, поэтому работаю на локальном хосте. Это мой файл / etc / nginx / sites-avaiable / default:

# You may add here your
# server {
#   ...
# }
# statements for each of your virtual hosts to this file

##
# You should look at the following URL's in order to grasp a solid understanding
# of Nginx configuration files in order to fully unleash the power of Nginx.
# http://wiki.nginx.org/Pitfalls
# http://wiki.nginx.org/QuickStart
# http://wiki.nginx.org/Configuration
#
# Generally, you will want to move this file somewhere, and start with a clean
# file but keep this around for reference. Or just disable in sites-enabled.
#
# Please see /usr/share/doc/nginx-doc/examples/ for more detailed examples.
##

server {
    listen 80 default_server;
    listen [::]:80 default_server ipv6only=on;

    root /usr/share/nginx/html;
    index index.php index.html index.htm;

    # Make site accessible from http://localhost/
    server_name localhost;

    location / {
        # First attempt to serve request as file, then
        # as directory, then fall back to displaying a 404.
        # try_files $uri $uri/ =404; this is default!
        try_files $uri $uri/ /index.php;
        # Uncomment to enable naxsi on this location
        # include /etc/nginx/naxsi.rules
    }

    # Only for nginx-naxsi used with nginx-naxsi-ui : process denied requests
    #location /RequestDenied {
    #   proxy_pass http://127.0.0.1:8080;    
    #}

    error_page 404 /404.html;

    # redirect server error pages to the static page /50x.html
    #
    error_page 500 502 503 504 /50x.html;
    location = /50x.html {
        root /usr/share/nginx/html;
    }

    # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
    #
    location ~ \.php$ {
        try_files $uri =404;
        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        fastcgi_pass unix:/var/run/php5-fpm.sock;
        fastcgi_index index.php;
        # fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; this is default!
        fastcgi_param   SCRIPT_FILENAME $request_filename;
        include fastcgi_params;
        }
    #   fastcgi_split_path_info ^(.+\.php)(/.+)$;
    #   # NOTE: You should have "cgi.fix_pathinfo = 0;" in php.ini
    #
    #   # With php5-cgi alone:
    #   fastcgi_pass 127.0.0.1:9000;
    #   # With php5-fpm:
    #   fastcgi_pass unix:/var/run/php5-fpm.sock;
    #   fastcgi_index index.php;
    #   include fastcgi_params;
    #}

    # deny access to .htaccess files, if Apache's document root
    # concurs with nginx's one
    #
    #location ~ /\.ht {
    #   deny all;
    #}
}


# another virtual host using mix of IP-, name-, and port-based configuration
#
#server {
#   listen 8000;
#   listen somename:8080;
#   server_name somename alias another.alias;
#   root html;
#   index index.html index.htm;
#
#   location / {
#       try_files $uri $uri/ =404;
#   }
#}


# HTTPS server
#
#server {
#   listen 443;
#   server_name localhost;
#
#   root html;
#   index index.html index.htm;
#
#   ssl on;
#   ssl_certificate cert.pem;
#   ssl_certificate_key cert.key;
#
#   ssl_session_timeout 5m;
#
#   ssl_protocols SSLv3 TLSv1 TLSv1.1 TLSv1.2;
#   ssl_ciphers "HIGH:!aNULL:!MD5 or HIGH:!aNULL:!MD5:!3DES";
#   ssl_prefer_server_ciphers on;
#
#   location / {
#       try_files $uri $uri/ =404;
#   }
#}

Я следую руководству здесь: http://www.codeigniter.com/user_guide/tutorial/static_pages.html

Это файл config.php CodeIgniter:

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

/*
|--------------------------------------------------------------------------
| Base Site URL
|--------------------------------------------------------------------------
|
| URL to your CodeIgniter root. Typically this will be your base URL,
| WITH a trailing slash:
|
|   http://example.com/
|
| If this is not set then CodeIgniter will try guess the protocol, domain
| and path to your installation. However, you should always configure this
| explicitly and never rely on auto-guessing, especially in production
| environments.
|
*/
$config['base_url'] = 'http://localhost/CodeIgniter-3.0.0/';


/*
|--------------------------------------------------------------------------
| Index File
|--------------------------------------------------------------------------
|
| Typically this will be your index.php file, unless you've renamed it to
| something else. If you are using mod_rewrite to remove the page set this
| variable so that it is blank.
|
*/
$config['index_page'] = '';

/*
|--------------------------------------------------------------------------
| URI PROTOCOL
|--------------------------------------------------------------------------
|
| This item determines which server global should be used to retrieve the
| URI string.  The default setting of 'REQUEST_URI' works for most servers.
| If your links do not seem to work, try one of the other delicious flavors:
|
| 'REQUEST_URI'    Uses $_SERVER['REQUEST_URI']
| 'QUERY_STRING'   Uses $_SERVER['QUERY_STRING']
| 'PATH_INFO'      Uses $_SERVER['PATH_INFO']
|
| WARNING: If you set this to 'PATH_INFO', URIs will always be URL-decoded!
*/
$config['uri_protocol'] = 'REQUEST_URI';

/*
|--------------------------------------------------------------------------
| URL suffix
|--------------------------------------------------------------------------
|
| This option allows you to add a suffix to all URLs generated by CodeIgniter.
| For more information please see the user guide:
|
| http://codeigniter.com/user_guide/general/urls.html
*/

$config['url_suffix'] = '';

/*
|--------------------------------------------------------------------------
| Default Language
|--------------------------------------------------------------------------
|
| This determines which set of language files should be used. Make sure
| there is an available translation if you intend to use something other
| than english.
|
*/
$config['language'] = 'english';

/*
|--------------------------------------------------------------------------
| Default Character Set
|--------------------------------------------------------------------------
|
| This determines which character set is used by default in various methods
| that require a character set to be provided.
|
| See http://php.net/htmlspecialchars for a list of supported charsets.
|
*/
$config['charset'] = 'UTF-8';

/*
|--------------------------------------------------------------------------
| Enable/Disable System Hooks
|--------------------------------------------------------------------------
|
| If you would like to use the 'hooks' feature you must enable it by
| setting this variable to TRUE (boolean).  See the user guide for details.
|
*/
$config['enable_hooks'] = FALSE;

/*
|--------------------------------------------------------------------------
| Class Extension Prefix
|--------------------------------------------------------------------------
|
| This item allows you to set the filename/classname prefix when extending
| native libraries.  For more information please see the user guide:
|
| http://codeigniter.com/user_guide/general/core_classes.html
| http://codeigniter.com/user_guide/general/creating_libraries.html
|
*/
$config['subclass_prefix'] = 'MY_';

/*
|--------------------------------------------------------------------------
| Composer auto-loading
|--------------------------------------------------------------------------
|
| Enabling this setting will tell CodeIgniter to look for a Composer
| package auto-loader script in application/vendor/autoload.php.
|
|   $config['composer_autoload'] = TRUE;
|
| Or if you have your vendor/ directory located somewhere else, you
| can opt to set a specific path as well:
|
|   $config['composer_autoload'] = '/path/to/vendor/autoload.php';
|
| For more information about Composer, please visit http://getcomposer.org/
|
| Note: This will NOT disable or override the CodeIgniter-specific
|   autoloading (application/config/autoload.php)
*/
$config['composer_autoload'] = FALSE;

/*
|--------------------------------------------------------------------------
| Allowed URL Characters
|--------------------------------------------------------------------------
|
| This lets you specify which characters are permitted within your URLs.
| When someone tries to submit a URL with disallowed characters they will
| get a warning message.
|
| As a security measure you are STRONGLY encouraged to restrict URLs to
| as few characters as possible.  By default only these are allowed: a-z 0-9~%.:_-
|
| Leave blank to allow all characters -- but only if you are insane.
|
| The configured value is actually a regular expression character group
| and it will be executed as: ! preg_match('/^[<permitted_uri_chars>]+$/i
|
| DO NOT CHANGE THIS UNLESS YOU FULLY UNDERSTAND THE REPERCUSSIONS!!
|
*/
$config['permitted_uri_chars'] = 'a-z 0-9~%.:_\-';


/*
|--------------------------------------------------------------------------
| Enable Query Strings
|--------------------------------------------------------------------------
|
| By default CodeIgniter uses search-engine friendly segment based URLs:
| example.com/who/what/where/
|
| By default CodeIgniter enables access to the $_GET array.  If for some
| reason you would like to disable it, set 'allow_get_array' to FALSE.
|
| You can optionally enable standard query string based URLs:
| example.com?who=me&what=something&where=here
|
| Options are: TRUE or FALSE (boolean)
|
| The other items let you set the query string 'words' that will
| invoke your controllers and its functions:
| example.com/index.php?c=controller&m=function
|
| Please note that some of the helpers won't work as expected when
| this feature is enabled, since CodeIgniter is designed primarily to
| use segment based URLs.
|
*/
$config['allow_get_array'] = TRUE;
$config['enable_query_strings'] = FALSE;
$config['controller_trigger'] = 'c';
$config['function_trigger'] = 'm';
$config['directory_trigger'] = 'd';

/*
|--------------------------------------------------------------------------
| Error Logging Threshold
|--------------------------------------------------------------------------
|
| If you have enabled error logging, you can set an error threshold to
| determine what gets logged. Threshold options are:
| You can enable error logging by setting a threshold over zero. The
| threshold determines what gets logged. Threshold options are:
|
|   0 = Disables logging, Error logging TURNED OFF
|   1 = Error Messages (including PHP errors)
|   2 = Debug Messages
|   3 = Informational Messages
|   4 = All Messages
|
| You can also pass an array with threshold levels to show individual error types
|
|   array(2) = Debug Messages, without Error Messages
|
| For a live site you'll usually only enable Errors (1) to be logged otherwise
| your log files will fill up very fast.
|
*/
$config['log_threshold'] = 0;

/*
|--------------------------------------------------------------------------
| Error Logging Directory Path
|--------------------------------------------------------------------------
|
| Leave this BLANK unless you would like to set something other than the default
| application/logs/ directory. Use a full server path with trailing slash.
|
*/
$config['log_path'] = '';

/*
|--------------------------------------------------------------------------
| Log File Extension
|--------------------------------------------------------------------------
|
| The default filename extension for log files. The default 'php' allows for
| protecting the log files via basic scripting, when they are to be stored
| under a publicly accessible directory.
|
| Note: Leaving it blank will default to 'php'.
|
*/
$config['log_file_extension'] = '';

/*
|--------------------------------------------------------------------------
| Log File Permissions
|--------------------------------------------------------------------------
|
| The file system permissions to be applied on newly created log files.
|
| IMPORTANT: This MUST be an integer (no quotes) and you MUST use octal
|            integer notation (i.e. 0700, 0644, etc.)
*/
$config['log_file_permissions'] = 0644;

/*
|--------------------------------------------------------------------------
| Date Format for Logs
|--------------------------------------------------------------------------
|
| Each item that is logged has an associated date. You can use PHP date
| codes to set your own date formatting
|
*/
$config['log_date_format'] = 'Y-m-d H:i:s';

/*
|--------------------------------------------------------------------------
| Error Views Directory Path
|--------------------------------------------------------------------------
|
| Leave this BLANK unless you would like to set something other than the default
| application/views/errors/ directory.  Use a full server path with trailing slash.
|
*/
$config['error_views_path'] = '';

/*
|--------------------------------------------------------------------------
| Cache Directory Path
|--------------------------------------------------------------------------
|
| Leave this BLANK unless you would like to set something other than the default
| application/cache/ directory.  Use a full server path with trailing slash.
|
*/
$config['cache_path'] = '';

/*
|--------------------------------------------------------------------------
| Cache Include Query String
|--------------------------------------------------------------------------
|
| Set this to TRUE if you want to use different cache files depending on the
| URL query string.  Please be aware this might result in numerous cache files.
|
*/
$config['cache_query_string'] = FALSE;

/*
|--------------------------------------------------------------------------
| Encryption Key
|--------------------------------------------------------------------------
|
| If you use the Encryption class, you must set an encryption key.
| See the user guide for more info.
|
| http://codeigniter.com/user_guide/libraries/encryption.html
|
*/
$config['encryption_key'] = '';

/*
|--------------------------------------------------------------------------
| Session Variables
|--------------------------------------------------------------------------
|
| 'sess_driver'
|
|   The storage driver to use: files, database, redis, memcached
|
| 'sess_cookie_name'
|
|   The session cookie name, must contain only [0-9a-z_-] characters
|
| 'sess_expiration'
|
|   The number of SECONDS you want the session to last.
|   Setting to 0 (zero) means expire when the browser is closed.
|
| 'sess_save_path'
|
|   The location to save sessions to, driver dependant.
|
|   For the 'files' driver, it's a path to a writable directory.
|   WARNING: Only absolute paths are supported!
|
|   For the 'database' driver, it's a table name.
|   Please read up the manual for the format with other session drivers.
|
|   IMPORTANT: You are REQUIRED to set a valid save path!
|
| 'sess_match_ip'
|
|   Whether to match the user's IP address when reading the session data.
|
| 'sess_time_to_update'
|
|   How many seconds between CI regenerating the session ID.
|
| 'sess_regenerate_destroy'
|
|   Whether to destroy session data associated with the old session ID
|   when auto-regenerating the session ID. When set to FALSE, the data
|   will be later deleted by the garbage collector.
|
| Other session cookie settings are shared with the rest of the application,
| except for 'cookie_prefix' and 'cookie_httponly', which are ignored here.
|
*/
$config['sess_driver'] = 'files';
$config['sess_cookie_name'] = 'ci_session';
$config['sess_expiration'] = 7200;
$config['sess_save_path'] = NULL;
$config['sess_match_ip'] = FALSE;
$config['sess_time_to_update'] = 300;
$config['sess_regenerate_destroy'] = FALSE;

/*
|--------------------------------------------------------------------------
| Cookie Related Variables
|--------------------------------------------------------------------------
|
| 'cookie_prefix'   = Set a cookie name prefix if you need to avoid collisions
| 'cookie_domain'   = Set to .your-domain.com for site-wide cookies
| 'cookie_path'     = Typically will be a forward slash
| 'cookie_secure'   = Cookie will only be set if a secure HTTPS connection exists.
| 'cookie_httponly' = Cookie will only be accessible via HTTP(S) (no javascript)
|
| Note: These settings (with the exception of 'cookie_prefix' and
|       'cookie_httponly') will also affect sessions.
|
*/
$config['cookie_prefix']    = '';
$config['cookie_domain']    = '';
$config['cookie_path']      = '/';
$config['cookie_secure']    = FALSE;
$config['cookie_httponly']  = FALSE;

/*
|--------------------------------------------------------------------------
| Standardize newlines
|--------------------------------------------------------------------------
|
| Determines whether to standardize newline characters in input data,
| meaning to replace \r\n, \r, \n occurences with the PHP_EOL value.
|
| This is particularly useful for portability between UNIX-based OSes,
| (usually \n) and Windows (\r\n).
|
*/
$config['standardize_newlines'] = FALSE;

/*
|--------------------------------------------------------------------------
| Global XSS Filtering
|--------------------------------------------------------------------------
|
| Determines whether the XSS filter is always active when GET, POST or
| COOKIE data is encountered
|
| WARNING: This feature is DEPRECATED and currently available only
|          for backwards compatibility purposes!
|
*/
$config['global_xss_filtering'] = FALSE;

/*
|--------------------------------------------------------------------------
| Cross Site Request Forgery
|--------------------------------------------------------------------------
| Enables a CSRF cookie token to be set. When set to TRUE, token will be
| checked on a submitted form. If you are accepting user data, it is strongly
| recommended CSRF protection be enabled.
|
| 'csrf_token_name' = The token name
| 'csrf_cookie_name' = The cookie name
| 'csrf_expire' = The number in seconds the token should expire.
| 'csrf_regenerate' = Regenerate token on every submission
| 'csrf_exclude_uris' = Array of URIs which ignore CSRF checks
*/
$config['csrf_protection'] = FALSE;
$config['csrf_token_name'] = 'csrf_test_name';
$config['csrf_cookie_name'] = 'csrf_cookie_name';
$config['csrf_expire'] = 7200;
$config['csrf_regenerate'] = TRUE;
$config['csrf_exclude_uris'] = array();

/*
|--------------------------------------------------------------------------
| Output Compression
|--------------------------------------------------------------------------
|
| Enables Gzip output compression for faster page loads.  When enabled,
| the output class will test whether your server supports Gzip.
| Even if it does, however, not all browsers support compression
| so enable only if you are reasonably sure your visitors can handle it.
|
| Only used if zlib.output_compression is turned off in your php.ini.
| Please do not use it together with httpd-level output compression.
|
| VERY IMPORTANT:  If you are getting a blank page when compression is enabled it
| means you are prematurely outputting something to your browser. It could
| even be a line of whitespace at the end of one of your scripts.  For
| compression to work, nothing can be sent before the output buffer is called
| by the output class.  Do not 'echo' any values with compression enabled.
|
*/
$config['compress_output'] = FALSE;

/*
|--------------------------------------------------------------------------
| Master Time Reference
|--------------------------------------------------------------------------
|
| Options are 'local' or any PHP supported timezone. This preference tells
| the system whether to use your server's local time as the master 'now'
| reference, or convert it to the configured one timezone. See the 'date
| helper' page of the user guide for information regarding date handling.
|
*/
$config['time_reference'] = 'local';

/*
|--------------------------------------------------------------------------
| Rewrite PHP Short Tags
|--------------------------------------------------------------------------
|
| If your PHP installation does not have short tag support enabled CI
| can rewrite the tags on-the-fly, enabling you to utilize that syntax
| in your view files.  Options are TRUE or FALSE (boolean)
|
*/
$config['rewrite_short_tags'] = FALSE;


/*
|--------------------------------------------------------------------------
| Reverse Proxy IPs
|--------------------------------------------------------------------------
|
| If your server is behind a reverse proxy, you must whitelist the proxy
| IP addresses from which CodeIgniter should trust headers such as
| HTTP_X_FORWARDED_FOR and HTTP_CLIENT_IP in order to properly identify
| the visitor's IP address.
|
| You can use both an array or a comma-separated list of proxy addresses,
| as well as specifying whole subnets. Here are a few examples:
|
| Comma-separated:  '10.0.1.200,192.168.5.0/24'
| Array:        array('10.0.1.200', '192.168.5.0/24')
*/
$config['proxy_ips'] = '';

Когда я перехожу по следующему URL-адресу:

http://127.0.0.1/CodeIgniter-3.0.0/index.php

страница индекса загружается успешно. Однако, когда я выполняю одно из следующих действий:

http://127.0.0.1/CodeIgniter-3.0.0/index.php/welcome
http://127.0.0.1/CodeIgniter-3.0.0/index.php/welcome/index
http://127.0.0.1/CodeIgniter-3.0.0/index.php/pages
http://127.0.0.1/CodeIgniter-3.0.0/index.php/pages/view

Nginx выдает ошибку 404. Мой контроллер Welcome.php - это файл по умолчанию:

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Welcome extends CI_Controller {

    /**
     * Index Page for this controller.
     *
     * Maps to the following URL
     *      http://example.com/index.php/welcome
     *  - or -
     *      http://example.com/index.php/welcome/index
     *  - or -
     * Since this controller is set as the default controller in
     * config/routes.php, it's displayed at http://example.com/
     *
     * So any other public methods not prefixed with an underscore will
     * map to /index.php/welcome/<method_name>
     * @see http://codeigniter.com/user_guide/general/urls.html
     */
    public function index()
    {
        $this->load->view('welcome_message');
    }
}

Как вы можете видеть выше, Welcome.php говорит:

     * Maps to the following URL
     *      http://example.com/index.php/welcome
     *  - or -
     *      http://example.com/index.php/welcome/index

но Nginx по-прежнему выдает ошибку 404. Первоначально я разместил этот вопрос на StackOverflow: https://stackoverflow.com/questions/31932160/php-codeigniter-nginx-throws-404-and-ignores-class-and-method

но я заметил, что решение аналогичной проблемы было найдено на ServerFault: Codeigniter в подкаталоге на Nginx 404

поэтому я решил разместить это и здесь. Заранее благодарю за любую помощь.