That means a connection was dropped. The "permanent error: 2" tells us that the socket is no longer viable due to distant party closing the connection.
Now, the reasons for closing the connection are many and diverse. It can be malign (something bad really happened) or benign (the user closed the browser for example).
For now, I can’t say more because I have no idea about the "big picture". If you can, please further explain your concerns or problems that you face.