problem when run the code

[yousry943]

when i run this code
$user->notify(new AccountApproved($user));
its show to me this error
This content encoding (f2a8896171cbf1adc538a0b80c0109d12d02178d) is not supported.
and you dont write in docmentation how can i get this varabile
$user->updatePushSubscription($endpoint, $key, $token, $contentEncoding);