q_connection = pika.BlockingConnection(
    pika.ConnectionParameters(
        host='127.0.0.1',
        virtual_host='/',
        credentials=pika.PlainCredentials(
            username='user',
            password='password'
        )
    )
)

channel = q_connection.channel()
channel.queue_declare(
    queue='processing',
    passive=False,
    durable=True,
    exclusive=False,
    auto_delete=False
)
channel.exchange_declare(exchange='router', type='direct', passive=False, durable=True, auto_delete=False)
channel.queue_bind('processing', 'router')

def callback(ch, method, properties, body):
    # действия над полученными сообщениями
    ...

    ch.basic_ack(delivery_tag=method.delivery_tag) # а вот тут периодически вылетает ошибка

channel.basic_consume(
    callback,
    queue='processing'
)
channel.start_consuming()