No supported encrypter found. The cipher and / or key length are invalid in webhost

my project worked well in localhost but it doesn't worked in web. after upload my project it give me this error

No supported encrypter found. The cipher and / or key length are invalid.
in EncryptionServiceProvider.php line 31
at EncryptionServiceProvider->Illuminate\Encryption\{closure}(object(Application), array()) in Container.php line 735
at Container->build(object(Closure), array()) in Container.php line

bla bla bla bla

some of tutorial says run command php artisan key:generate but doesn't make me any sense how could that in webhost ? i can run any command in localhost but how can i do that in webhost? or Is there any other options to overflow.?

via Chebli Mohamed