The cause of the bug
In the lightweight backend service built by node (the main function is to forward requests and undertake part of data processing), some time-consuming interfaces will generate this error, which means that they are closed before the interface request is completed.
I checked the reason, because the httpServer of nodejs has a default timeout of two minutes, that is, if the response time of an interface in node exceeds two minutes, the connection will be closed.
Solution
Set the timeout time of httpServer a little longer or set it to 0 to keep the connection