When deploying a CodeIgniter application to a web hosting service, it’s important to correctly configure the file structure to ensure that the application functions properly.

Move index.php to public_html:

• Place the index.php file inside the public_html directory. This directory is the entry point for the public-facing part of your application.

Move Other Directories Outside public_html:

• Move the application/, system/, and vendor/ (if using Composer) directories outside of public_html. This ensures that sensitive application files are not directly accessible from the web.

Sample structure,

/home/user/
│
├── application/          // Application files (outside public_html)
├── system/               // System files (outside public_html)
├── public_html/          // Publicly accessible directory
│   └── index.php         // Entry point of the application
│   └── assets/           // Static files (CSS, JS, images, etc.)

Try this way and hope this resolves the issue.