RuntimeException in EncryptionServiceProvider.php line 29: o que fazer?

[Luiz Morais Junior]

Erro o subir a aplicação com o comando:

php artisan serve

pode ser a minha instalação do xampp??

Segue o erro:

Whoops, looks like something went wrong.

1/1RuntimeException in EncryptionServiceProvider.php line 29:No supported encrypter found. The cipher and / or key length are invalid.

1. in EncryptionServiceProvider.php line 29
2. at EncryptionServiceProvider->Illuminate\Encryption\{closure}(object(Application), array()) in Container.php line 734
3. at Container->build(object(Closure), array()) in Container.php line 627
4. at Container->make('encrypter', array()) in Application.php line 674
5. at Application->make('Illuminate\Contracts\Encryption\Encrypter') in Container.php line 838
6. at Container->resolveClass(object(ReflectionParameter)) in Container.php line 801
7. at Container->getDependencies(array(object(ReflectionParameter)), array()) in Container.php line 772
8. at Container->build('estoque\Http\Middleware\EncryptCookies', array()) in Container.php line 627
9. at Container->make('estoque\Http\Middleware\EncryptCookies', array()) in Application.php line 674
10. at Application->make('estoque\Http\Middleware\EncryptCookies') in Pipeline.php line 123
11. at Pipeline->Illuminate\Pipeline\{closure}(object(Request)) in CheckForMaintenanceMode.php line 42
12. at CheckForMaintenanceMode->handle(object(Request), object(Closure))
13. at call_user_func_array(array(object(CheckForMaintenanceMode), 'handle'), array(object(Request), object(Closure))) in Pipeline.php line 124
14. at Pipeline->Illuminate\Pipeline\{closure}(object(Request))
15. at call_user_func(object(Closure), object(Request)) in Pipeline.php line 103
16. at Pipeline->then(object(Closure)) in Kernel.php line 122
17. at Kernel->sendRequestThroughRouter(object(Request)) in Kernel.php line 87
18. at Kernel->handle(object(Request)) in index.php line 54
19. at require_once('C:\xampp\htdocs\estoque\public\index.php') in server.php line 21

[Luiz Morais Junior]

Executei o comando abaixo e funcionou:

php artisan key:generate