My Laravel 5.5 app not working on remote server namecheap VPS after deployment but working fine on local server with WAMP

Everything about this app is working fine on my local sever, but refused to work remotely. if i visit the app www.mysite.com. It always shows internal server error. Though i don't have any route in web.php but i expected to redirect back to 404 not found page but not doing that but it does on localhost.

The other main problem is , i have many routes in api.php, if i send data to any of the routes, they accept data and might even save them in database where it is necessary but it will never return the json Response that i have defined after every successful operation. The response i always get is 500 internal server error even if the operation was successful. I have been on this issue for over two weeks now.

I am using PHP 7.2 on the server

Here is my .htaccess file

<IfModule mod_rewrite.c>
    <IfModule mod_negotiation.c>
        Options -MultiViews -Indexes
    </IfModule>
    RewriteEngine On
    RewriteBase /
    # Handle Authorization Header
    RewriteCond %{HTTP:Authorization} .
    RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
    # Redirect Trailing Slashes If Not A Folder...
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteCond %{REQUEST_URI} (.+)/$
    RewriteRule ^ %1 [L,R=301]
    # Handle Front Controller...
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteRule ^ index.php [L]
</IfModule>

api.php

<?php

Route::group(['prefix' => 'user', 'namespace' => 'User'], function () {

    Route::post('/login', 'UserAuthController@userLogin');
    Route::post('/signup', 'UserAuthController@userSignup');

});

UserController.php

public function userSignup(Request $request)
    {
        $rules = [
            'name' => 'required|string|max:200',
            'password' => 'required|between:8,100|confirmed',
            'phone' => 'unique:users|required|digits:11|numeric',
            'email' => 'unique:users|required|email',

        ];
        $validator = Validator::make($request->all(), $rules);
        $code = mt_rand(100000, 900000);
        $hCode = FacadesHash::make($code);
        if ($validator->passes()) {
            $user = User::create([
                'name' => $request['name'],
                'email' => $request['email'],
                'phone' => $request['phone'],
                'otp' => $hCode,
                'password' => FacadesHash::make($request['password']),
            ]);

            $data = [
                'name' => $request['name'], 'subject' => 'Email Confirmation',
                'view' => 'mails.emailconfirm', 'code' => $code
            ];


            return response()->json(['success' => true, 'status' => 200, 'message' => 'Your account has been created successfully and an OTP code has been sent to your email'], 200);
        } else {

            return response()->json(['success' => false, 'status' => 200, 'message' => $validator->errors()->first()], 200);
        }
    }

the signup route for example, is working fine but will never return the Json response i specified, it will rather return 500 internal server error even if everything went well.

No error is being logged in my storage/log if everything went well and i dont get the response. But i do see error there if the operation was not successful.

all folders have 777 permissions and i have as well clear all caches so many times

via Chebli Mohamed