multiple refresh on browser with laravel 5.4 project get error "Whoops, looks like something went wrong."

When i actually refresh my blade view for multiple times i will get error message "Whoops, looks like something went wrong." in laravel 5.4 but there are no error in my code and no error message display only a header "Whoops, looks like something went wrong."

i try to copy .env.example to .env but i got error message

RuntimeException in Encrypter.php line 43:
The only supported ciphers are AES-128-CBC and AES-256-CBC with the correct key lengths.

why only refresh blade view on browser get error is anyone can tell me what is this error message?? and how to fix this??

via Chebli Mohamed