Codeigniter: Call to a member function item() on a non-object - codeigniter-2

Question

I have installed Codeigniter 2.1.0 locally, it works great.
But when I upload it to my provider I first get:
Your system folder path does not appear to be set correctly. Please open the following file and correct this: index.php
I can fix this by changing index.php:
$system_path = "system";
$application_folder = "application";
to (why? I never had to do this...)
$system_path = dirname(__FILE__) . "/system";
$application_folder = dirname(__FILE__) . "/application";
But then I get:
Fatal error: Call to a member function item() on a non-object in <path>/Utf8.php on line 47
I can comment out the line but I then get similar error somewhere else.
Please, is this problem at my provider? Or am I doing something wrong? I used CI before and it worked elsewhere flawlessly.
PS: Please not this is completely fresh install of CI.

Answer 1

Yes and no,
the problem is that your provider has probably different web server settings than you do. If he does, you have to adapt the settings, that fits the needs.
The main root cause of this problem is the variety of styles that can express path in the file system. *NIX systems uses forward-slash for expressing folder structure. On Windows machines its a back-slash.
The *NIX systems have root of the file system "/", Windows machines has C:/, D:/ etc...
Every file system has different settings of access rights and their management.
On most of the UNIX systems works locating of the path without a trouble. So if codeigniter tries to determine absolute path of the directory where is CI located, from the "so called" relative directory, he will succeed. If not, it can't work because he don't know where are the files it wants to load.
There are also many bugs across the PHP versions. Eg. there is reported bug with PHP 5.2.0 and Windows Apache that (with certain rights on the directory) the is_dir() function returns False even if the directory is present and it should (and on the other system will) return True.
The most certain way to ensure the path is loaded correctly is to give the CI absolute path. The absolute path varies on OS and eg. on UNIX is /var/www/domain.com/system, on Windows "who knows?". But there is a way how to determine it easily.
Create index.php file in the root folder you can access with this content inside:
<?php phpinfo(); ?>
If you load the page there will be (among other things) stated the absolute path in row with:
_SERVER["DOCUMENT_ROOT"] | /var/www/mydomain.com/
Now if you will assign the absolute path to the $system_path variable it should be sufficient. For greater certainty also assign $application_folder variable.
Note that the path to system folder has to be to the system folder of code igniter and path to application folder has to be to the application folder. So for example:
$system_path = "/var/www/mydomain.com/system";
$application_folder = "/var/www/mydomain.com/application";
After that your site should work flawlessly.
(there are some mentions about this on user guide: http://ellislab.com/codeigniter/user-guide/installation/index.html)