I am new to the codeigniter 4.0 framework and been trying to upgrade my old code from 3.0 to 4.0 and in the meantime learn the new framework. Currently I am running into an issue which I cannot explain is quite frustrating.

I’ve got a Controller called Account.php located in the AppControllers directory.

<?php

namespace AppControllers;

use AppModelsAccountModel;

class Account extends BaseController
{

    private $accountModel;
    private $validation;

    public function __construct()
    {
        // Load the Account_model globally in the constructor        
        $this->accountModel = new AccountModel();
        $this->validation = ConfigServices::validation();
    }

    public function signup_process()
    {
        // Set validation rules
        $this->validation->setRules([
            'username'          => 'required|max_length[50]',
            'email'             => 'required|valid_email|max_length[250]',
            'firstname'         => 'required|max_length[50]',
            'lastname'          => 'required|max_length[50]',
            'birthday'          => 'required|valid_date',
            'discord'           => 'max_length[50]',
        ]);

        // Validation failed, redirect back to the form with validation errors
        if (!$this->validation->withRequest($this->request)->run()) {            
            return redirect()->back()->withInput()->with('errors', $this->validation->getErrors());
        
        } 
        // If validation passes, proceed with form processing
        else 
        {
            // Access form data
            $request = service('request');
            $arrUser['username']    = $request->getPost('username');
            $arrUser['email']       = $request->getPost('email');
            $arrUser['firstname']   = $request->getPost('firstname');
            $arrUser['lastname']    = $request->getPost('lastname');
            $arrUser['birthday']    = $request->getPost('birthday');
            $arrUser['discord']     = $request->getPost('discord');

            // Insert user data into the database using the model
            $this->accountModel->insert_user($arrUser);

            return redirect()->to('/account/signup-done');
        }
        
    }
}

And I am trying to call a function in my AccountModel.php file located in the AppModels directory

<?php

namespace AppModels;

use CodeIgniterModel;

class AccountModel extends Model
{
    public function insert_user($arrUser) 
    {
        print_r($arrUser)
    }
}

As soon as I turn on the code $this->accountModel = new AccountModel();, I am greeted with the default Codeigniter error message

Whoops!
We seem to have hit a snag. Please try again later…

I’ve tried looking through the documentation of the framework, but can’t find a clear explanation what might be going wrong.