Node red automatically disconnected from server in windows10

node red automatically disconnected from server, with message "node red automatically disconnected from server"

LOG:

C:\Users\YASH ZADE>node-red
6 Nov 10:05:49 - [info]

Welcome to Node-RED
===================

6 Nov 10:05:49 - [info] Node-RED version: v1.2.3
6 Nov 10:05:49 - [info] Node.js  version: v15.0.1
6 Nov 10:05:49 - [info] Windows_NT 10.0.19041 x64 LE
6 Nov 10:05:50 - [info] Loading palette nodes
6 Nov 10:05:51 - [info] Settings file  : C:\Users\YASH ZADE\.node-red\settings.js
6 Nov 10:05:51 - [info] Context store  : 'default' [module=memory]
6 Nov 10:05:51 - [info] User directory : \Users\YASH ZADE\.node-red
6 Nov 10:05:51 - [warn] Projects disabled : editorTheme.projects.enabled=false
6 Nov 10:05:51 - [info] Flows file     : \Users\YASH ZADE\.node-red\flows_DESKTOP-H7PHD6A.json
6 Nov 10:05:51 - [info] Server now running at http://127.0.0.1:1880/
6 Nov 10:05:51 - [info] Starting flows
6 Nov 10:05:51 - [info] Started flows

C:\Users\YASH ZADE>

I don't see the error message in the log you provided.
If it appears in the debug pane it is probably coming from one of the nodes in your flow (meaning node red has disconnected from a server of some sort that you have configured). Show us a screenshot of the message. If the message has a node name or id above it then search for that name or id using Ctrl+F to find which node it is.
Nodejs 15 is not yet recommended for node-red (and probably never will be, the next recommended version will be 16 I think). That could be the problem if a node you are using is not compatible with nodejs 15.

thanks for your reply.
the problem: whenever I press deploy button my connection get lost. the nodes I am using is firebase node.

I don't know about the Firebase node, but if you show us how you have configured it and what, if anything, you are sending to it then someone may be able to help, however you might be better to start a new thread with Firebase in the title so that someone who knows about it might see it.