Codeigniter 4 - Call to undefined function App\Controllers\base_url() on live server

Question

Codeigniter 4 base_url() is working fine on localhost (even using ip addresses like http://192.168.0.2/)

But on uploading it on a live server, i get the error below.

Call to undefined function App\Controllers\base_url()

I have set the base_url in the App\Config\App.php file and tried to autload the url helper in App\Config\BaseController.php file as shown below

public $baseURL = 'http://domainname.com/'; // App.php file

protected $helpers = ['url']; // BaseController.php file

I also tried to load the url_helper in the controller function like

helper('url'); // my_controller.php file

I didn't change anything in the .htaccess file. Its the same that comes with ci4 installation.

Any idea what might be causing the issue?

The .htaccess file is as follows:

# Disable directory browsing
Options All -Indexes

# ----------------------------------------------------------------------
# Rewrite engine
# ----------------------------------------------------------------------

# Turning on the rewrite engine is necessary for the following rules and features.
# FollowSymLinks must be enabled for this to work.
<IfModule mod_rewrite.c>
    Options +FollowSymlinks
    RewriteEngine On

    # If you installed CodeIgniter in a subfolder, you will need to
    # change the following line to match the subfolder you need.
    # http://httpd.apache.org/docs/current/mod/mod_rewrite.html#rewritebase
    # RewriteBase /

    # Redirect Trailing Slashes...
    RewriteCond %{REQUEST_FILENAME} !-d
        RewriteRule ^(.*)/$ /$1 [L,R=301]

    # Rewrite "www.example.com -> example.com"
    RewriteCond %{HTTPS} !=on
    RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]
    RewriteRule ^ http://%1%{REQUEST_URI} [R=301,L]

    # Checks to see if the user is attempting to access a valid file,
    # such as an image or css document, if this isn't true it sends the
    # request to the front controller, index.php
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteRule ^(.*)$ index.php/$1 [L]

    # Ensure Authorization header is passed along
    RewriteCond %{HTTP:Authorization} .
    RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
</IfModule>

<IfModule !mod_rewrite.c>
    # If we don't have mod_rewrite installed, all 404's
    # can be sent to index.php, and everything works as normal.
    ErrorDocument 404 index.php
</IfModule>

# Disable server signature start
    ServerSignature Off
# Disable server signature end

Answer 1

It turns out that my System Files had been corrupted just like TimBrownlaw had pointed out.

Then main and most likely problem to cause this issue is if the url_helper is broken.

But I fixed the issue by re-downloading and uploading the core files for Code Igniter 4.