Set the LC_ALL environment variable to a valid locale - postgresql

Question

To resolve postgresql conflicts (see my previous question), I've installed postgre-common brew install petere/postgresql/postgresql-common and postgre#12. Then create my cluster pg_createcluster 12 main.
There's already a content in the local DB, created 1 year ago, which I can no more access, because environment postgre 11 cannot acces DB initialized with postgre 12.
But when I launch pg_ctlcluster 12 main start.
Cluster was created successfully, appears on list pg_lscluster, can be dropped with pg_dropcluster and recreated susscessfully :
pg_ctlcluster 12 main start
background-jobs-demo git:(master) ✗ pg_createcluster 12 main
Creating new PostgreSQL cluster 12/main ...
/usr/local/opt/postgresql#12/bin/initdb -D /usr/local/var/lib/postgresql/12/main --auth-local peer --auth-host md5
The files belonging to this database system will be owned by user "pierre".
This user must also own the server process.
The database cluster will be initialized with locale "en_US.UTF-8".
The default database encoding has accordingly been set to "UTF8".
The default text search configuration will be set to "english".
Data page checksums are disabled.
fixing permissions on existing directory /usr/local/var/lib/postgresql/12/main ... ok
creating subdirectories ... ok
selecting dynamic shared memory implementation ... posix
selecting default max_connections ... 100
selecting default shared_buffers ... 128MB
selecting default time zone ... Europe/Paris
creating configuration files ... ok
running bootstrap script ... ok
performing post-bootstrap initialization ... ok
syncing data to disk ... ok
Success. You can now start the database server using:
'/usr/local/opt/postgresql#12/bin/pg_ctl' -D /usr/local/var/lib/postgresql/12/main -l logfile start
Ver Cluster Port Status Owner Data directory Log file
12 main 5432 down pierre /usr/local/var/lib/postgresql/12/main /usr/local/var/log/postgresql/postgresql-12-main.log
But cluster doesn't start.
Error: /usr/local/opt/postgresql#12/bin/pg_ctl /usr/local/opt/postgresql#12/bin/pg_ctl start -D /usr/local/var/lib/postgresql/12/main -l /usr/local/var/log/postgresql/postgresql-12-main.log -s -o -c config_file="/usr/local/etc/postgresql/12/main/postgresql.conf" -c external_pid_file="/usr/local/var/run/postgresql/12-main.pid" exited with status 1:
2021-12-04 22:44:50.632 CET [76694] LOG: starting PostgreSQL 12.9 (Homebrew petere/postgresql) on x86_64-apple-darwin16.7.0, compiled by Apple LLVM version 9.0.0 (clang-900.0.39.2), 64-bit
2021-12-04 22:44:50.636 CET [76694] LOG: listening on IPv6 address "::1", port 5432
2021-12-04 22:44:50.636 CET [76694] LOG: listening on IPv4 address "127.0.0.1", port 5432
2021-12-04 22:44:50.638 CET [76694] LOG: listening on Unix socket "/tmp/.s.PGSQL.5432"
2021-12-04 22:44:50.651 CET [76694] FATAL: postmaster became multithreaded during startup
2021-12-04 22:44:50.651 CET [76694] HINT: Set the LC_ALL environment variable to a valid locale.
2021-12-04 22:44:50.652 CET [76694] LOG: database system is shut down
pg_ctl: could not start server
Examine the log output.
On my shell, the locales values are
LANG="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_CTYPE="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_ALL="en_US.UTF-8"
How shall I set locale LC_ALL value for postgresql#12 ?
The helpful link https://github.com/PostgresApp/PostgresApp/issues/317#issuecomment-251786830 is for postgre9.6, and I can't find how to set locale LC_ALL value for postgresql#12.
I've tried different things that didn't work :
add lc_all='C' or lc_all='en_US.UTF-8'
in /usr/local/var/postgresql#12/postgresql.conf,
add lc_all='C'
in /usr/local/var/postgresql#12/postgresql.conf,