无法在laravel中进行身份验证

I have this error in Laravel latest for authentication

Argument 2 passed to Illuminate\Auth\SessionGuard::__construct() must be an instance of Illuminate\Contracts\Auth\UserProvider, null given, called in G:\xampp\htdocs ewrestaurantcrm\vendor\laravel\framework\src\Illuminate\Auth\AuthManager.php

can anyone give me an idea about this error why this error is occurring? I am using below code for authentication in my Auth\AuthController.php file

protected function login(Request $request) {
    $email = $request->email;
    $password = bcrypt($request->password);
    if (Auth::login(['email' => $email, 'password' => $password])) {
        return redirect()->intended('/admin/dashboard');
    }
}

When you are authenticate user against email and password then use Auth::attempt or Auth::once (For single request). When we have user instance and we want to login with that user instance then we use Auth::login. For your case use Auth::attempt like this

public function login(Request $request) {
    $email = $request->email;
    $password = bcrypt($request->password);
    if (Auth::attempt(['email' => $email, 'password' => $password])) {
        return redirect()->intended('/admin/dashboard');
    }
}

Details: https://laravel.com/docs/5.6/authentication#included-authenticating

Change your code to

public function login(Request $request) {
    $email = $request->get('email');
    $password = $request->get('password');
    if (Auth::attempt(['email' => $email, 'password' => $password])) {
        return redirect()->intended('/admin/dashboard');
    }
}

I changed the protected to public, Auth::login() to Auth::attempt(). If you use login, you will actually have to pass the User object you like to login as. You do not need to encrypt the password to pass to attempt and. To make this simpler you can write

public function login(Request $request) {
    if (Auth::attempt($request->only('email', 'password'))) {
        return redirect()->intended('/admin/dashboard');
    }
}

This of course assumes that your form has correct name for fields, email and password and also has same field email and password in users table as well.