BUG #18143: pg_upgrade fails to use port 50432 even with firewall disabled

The following bug has been logged on the website:

Bug reference: 18143
Logged by: Hans Buschmann
Email address: buschmann(at)nidsa(dot)net
PostgreSQL version: 16.0
Operating system: Windows 11
Description:

When upgrading from pg15.4 to pg16.0 pg_upgrade failed to start the old (and
probably) also the new cluster when using the default upgrade port like
50432.

The error log gives no hint why the cluster fails to start:

command: "N:/pgsql_pg15/bin/pg_ctl" -w -l
"N:/pgdata/data/pg_upgrade_output.d/20231002T124057.688/log/pg_upgrade_server.log"
-D "N:/pgdata/data_pg15" -o "-p 50432 -b " start >>
"N:/pgdata/data/pg_upgrade_output.d/20231002T124057.688/log/pg_upgrade_server_start.log"
2>&1
warte auf Start des Servers.... Warten beendet
pg_ctl: konnte Server nicht starten
Prüfen Sie die Logausgabe.

When specifying
--old-port=5442 --new-port=5443 --link

at the end of the pg_upgrade command the upgrade succeeds.

To avoid any trouble, the firewall was disabled before running the
upgrade.

The reason for the failure is not really obvious and requires quite some
experience to try other ports on the users own behalf.

Thank you for looking.

Hans Buschmann