PusherBroacaster does not work on Laravel 5.5

Can someone help me on this? I can not find out what caused the issue.

I was working on a simple real-time chatroom then I can not able to use Laravel PusherBroadcaster broadcast to Pusher. But it works if I use the Pusher API directly. All the functions work on Laravel 5.4 , but after I upgrade to 5.5 then I saw this error message pop up. it looks something wrong when Larvel initializes the Pusher instance. but when I dump the Pusher instance. It looks the same to me.

The following is the error message. (I removed my Auth Key)

[Illuminate\Broadcasting\BroadcastException] Invalid signature: you should have sent HmacSHA256Hex("POST\n/apps/403050/events\nauth_key=***********&auth_timest amp=1506693541&auth_version=1.0&body_md5=bb65697e4eead004acf616b145823887", your_secret_key), but you sent "d1757053fc729c8 34335698d56b6bc3c83c339e01b82ee40df4a1be45329e48e"

And following is the response (I also remove the Auth Key)

curl resource {@421 url: "http://api.pusherapp.com:80/apps/403050/events?auth_key=*********&auth_signature=75b54f00fb6140fe11e0d35f179fb6eda21c6ac9c9d72d380a3d35b2b9fa3670&auth_timestamp=1506694322&auth_version=1.0&body_md5=7e592edea5f1aa5fbae31cfe59f70388" content_type: "text/html;charset=utf-8" http_code: 401 header_size: 127 request_size: 449 filetime: -1 ssl_verify_result: 0 redirect_count: 0 total_time: 0.281 namelookup_time: 0.063 connect_time: 0.172 pretransfer_time: 0.172 size_upload: 86.0 size_download: 297.0 speed_download: 1056.0 speed_upload: 306.0 download_content_length: 297.0 upload_content_length: 86.0 starttransfer_time: 0.281 redirect_time: 0.0 redirect_url: "" primary_ip: "34.205.251.152" certinfo: [] primary_port: 80 local_ip: "192.168.1.110" local_port: 50100 }