80017: Connection closed

The connection was closed deliberately, rather than dropped. This is the expected outcome when the connection is closed by request and is not a fault.

What you should do

Nothing, if you closed the connection on purpose. If you didn't expect it, an operation was attempted on a connection that had already been closed; check the connection state before acting on it, or open a new connection first.

Why it happens

The connection was closed by request, and then either reported as closed or acted on after closing. Closing is deliberate and final for that connection, so it is not a fault in itself.

What you'll see

The error is reported with code 80017 and HTTP status 400. The message is typically Connection closed.