Laravel phpunit's default code returns me status 500 on working home page

I have running project on localhost port 8000, and at first seek it opens home page ('/') perfecly but for some reasons

<?php

namespace Tests\Feature;

use Illuminate\Foundation\Testing\RefreshDatabase;
use Tests\TestCase;

class ExampleTest extends TestCase
{
    /**
     * A basic test example.
     *
     * @return void
     */
    public function testBasicTest()
    {
        $response = $this->get('/');

        $response->assertStatus(200);
    }
}

code returns me 500 not 200.

Time: 1 second, Memory: 22.00 MB

There was 1 failure:

1. Tests\Feature\ExampleTest::testBasicTest Expected status code 200 but received 500. Failed asserting that 200 is identical to 500.

Why from controller it opens page but test fails?