pg_upgrade from Postgresql-12 to Postgresql-13 fails with "Creating dump of database schemas postgres *failure*"

Hi I hope I send this to the right mailing list and able to get some help. 

I was trying to perform `pg_upgrade` from Postgresql-12 to Postgresql-13 (after being advised that upgrading from Postgresql-12 to Postgresql-14 is biting off much more than I could chew... ).

The `pg_upgrade --check` went through OK. But the actual `pg_upgrade` always get error at the step of Creating dump of database schemas for `postgres` database.

```

/usr/lib/postgresql/13/bin/pg_upgrade --old-datadir=/bnas/pgdata/postgresql/12/main --new-datadir=/bnas/pgdata/postgresql/13/main --old-bindir=/usr/lib/postgresql/12/bin --new-bindir=/usr/lib/postgresql/13/bin --old-options '-c config_file=/etc/postgresql/12/main/postgresql.conf' --new-options '-c config_file=/etc/postgresql/13/main/postgresql.conf' --check

Performing Consistency Checks

-----------------------------

Checking cluster versions ok

Checking database user is the install user ok

Checking database connection settings ok

Checking for prepared transactions ok

Checking for system-defined composite types in user tables ok

Checking for reg* data types in user tables ok

Checking for contrib/isn with bigint-passing mismatch ok

Checking for presence of required libraries ok

Checking database user is the install user ok

Checking for prepared transactions ok

Checking for new cluster tablespace directories ok

*Clusters are compatible*

postgres@ual:~$ /usr/lib/postgresql/13/bin/pg_upgrade --old-datadir=/bnas/pgdata/postgresql/12/main --new-datadir=/bnas/pgdata/postgresql/13/main --old-bindir=/usr/lib/postgresql/12/bin --new-bindir=/usr/lib/postgresql/13/bin --old-options '-c config_file=/etc/postgresql/12/main/postgresql.conf' --new-options '-c config_file=/etc/postgresql/13/main/postgresql.conf'

Performing Consistency Checks

-----------------------------

Checking cluster versions ok

Checking database user is the install user ok

Checking database connection settings ok

Checking for prepared transactions ok

Checking for system-defined composite types in user tables ok

Checking for reg* data types in user tables ok

Checking for contrib/isn with bigint-passing mismatch ok

Creating dump of global objects ok

Creating dump of database schemas

postgres

*failure*

Consult the last few lines of "pg_upgrade_dump_13427.log" for

the probable cause of the failure.

Failure, exiting

```

Here are the logs: pg_upgrade_server.log, pg_upgrade_dump_13427.log and tail_postgresql-12-2022-02-16_190344.log.

Additional information:

1. An observation on `pg_upgrade --check`. I could not run actual `pg_upgrade` directly after the `--check` operation as I will always get some `server not shut down properly` error.

2. I have PostGIS and a couple other audit/monitoring extensions installed on Postgresql-12. I have installed the similar Ubuntu PostGIS packages for Postgresql-13. Do I need to run `CREATE EXTENSIONS xxx` before performing the `pg_upgrade`?

Have been stuck with this for over a week now, and sincerely hope someone could help me. TIA.

chow