Symfony\Component\Debug\Exception\FatalThrowableError : Class 'Model' not found

执行 php artisan db:seed 命令报的错：
我批量生成不了数据。怎么办？

vagrant@homestead:~/Code/weibo$ php artisan db:seed
Symfony\Component\Debug\Exception\FatalThrowableError : Class 'Model' not found
at /home/vagrant/Code/weibo/database/seeds/DatabaseSeeder.php:14
10| @return void
11| /
12| public function run()
13| {

14| Model::unguard();
15|
16| $this->call(UsersTableSeeder::class);
17|
18| Model::reguard();
Exception trace:
1 DatabaseSeeder::run()
/home/vagrant/Code/weibo/vendor/laravel/framework/src/Illuminate/Container/BoundMethod.php:32
2 call_user_func_array([])
/home/vagrant/Code/weibo/vendor/laravel/framework/src/Illuminate/Container/BoundMethod.php:32
Please use the argument -v to see more details.
vagrant@homestead:~/Code/weibo$