Upgrade 9.4 to 12 on windows system

Hello my friends,

I want to upgrade my Postgres DBMS 9.4 to 12 on the Windows system. I
follow these steps on this website. (
https://qasymphony.zendesk.com/hc/en-us/articles/115002398166-09-Upgrade-PostgreSQL-9-4-to-9-5-on-Windows
)
However when everything goes ok, the same error is raising in every cmd
running.

Performing Consistency Checks
-----------------------------
Checking cluster versions ok

*failure*
Consult the last few lines of "pg_upgrade_server_start.log" or
"pg_upgrade_server.log" for
the probable cause of the failure.

connection to database failed: could not connect to server: Connection
refused (0x0000274D/10061)
Is the server running on host "localhost" (::1) and accepting
TCP/IP connections on port 50432?
could not connect to server: Connection refused (0x0000274D/10061)
Is the server running on host "localhost" (127.0.0.1) and accepting
TCP/IP connections on port 50432?
could not connect to source postmaster started with the command:
"C:/Program Files/PostgreSQL/9.4/bin/pg_ctl" -w -l "pg_upgrade_server.log"
-D "C:/Program Files/PostgreSQL/9.4/data" -o "-p 50432 -b " start

I ran this upgrade on Windows Server 12 64 bit. I researched this error
and why it raises but I don't find any proper solution. If anyone relates
this problem, I can share my log files.

Thanks.