mcrypt_encrypt(): Key of size 4 not supported by this algorithm. Only keys of sizes 16, 24 or 32 supported

I have changed my APP_KEY in .env file to 32char string , but it didnt work.

other than this error it also showed some other errors like UNDEFINEDINDEX : APP_KEY Undefined index: APP_DEBUG UNDEFINED INDEX : HTTP_HOST UNDEFINED INDEX : DB_HOST and almost all content of .env file are the right hand side of undefined index example UNDEFINED INDEX : DB_HOST

via Chebli Mohamed