Why i get error using accept() method in pybluez?

I wanna make a simple connection between raspberry and phone but every time i write .accept() i get [Errno 77] File descriptor in bad state. Here is the code:

import bluetooth
s = bluetooth.BluetoothSocket(bluetooth.RFCOMM)
port = 19
host = "MACADDR"
s.connect((host,port))
client, badr = s.accept()

The problem is that you mixed up both client and server logic in the given code snippet. Once connect() is called the socket becomes a client, so indeed trying to call accept() after that would fail. Simply remove client, badr = s.accept() to make the client side work.

Below is an example of the client side implementation:

import bluetooth

def client(remote_addr: str, remote_port: int):
    client_sock = bluetooth.BluetoothSocket(bluetooth.RFCOMM)
    print(f'Establishing connection to {remote_addr}:{remote_port}')
    client_sock.connect((remote_addr, remote_port))
    print('Connection established')
    return client_sock

and here is an example of the server side implementation:

import bluetooth

def server(local_addr: str, local_port: int):
    server_sock = bluetooth.BluetoothSocket(bluetooth.RFCOMM)
    server_sock.bind((local_addr, local_port))
    server_sock.listen(1)

    print('Listening for connection on {local_addr}:{local_port}...')
    client_sock, remote_addr = server_sock.accept()
    print(f'Device {remote_addr} connected')
    return (server_sock, client_sock)

You can run server() on the raspberry and client() on the phone, or vice versa.