Pre-5.1 config/app.php contains:
'cipher' => MCRYPT_RIJNDAEL_128,
Debian servers don't install mcrypt by default, our Docker image does.
Now Laravel starter template offers another cipher and to get rid of a default value for APP_KEY:
config/app.php
/* |-------------------------------------------------------------------------- | Encryption Key |-------------------------------------------------------------------------- | | This key is used by the Illuminate encrypter service and should be set | to a random, 32 character string, otherwise these encrypted strings | will not be safe. Please do this before deploying an application! | */ 'key' => env('APP_KEY'), 'cipher' => 'AES-256-CBC',