Emitted when processing has failed for a message; this could mean either that it could not be read (if request_read has not been emitted for it yet), or that the response could not be written back (if request_read has been emitted but request_finished has not been).
message is in an undefined state when this signal is emitted; the signal exists primarily to allow the server to free any
state that it may have allocated in request_started.
| client |
the client context |
| message |
the message |