LDAP Result Code 206 Empty password not allowed by the client

[apau2025]

We are testing to upgrade our ldap2pg from v5.x into v6.x. With my current ldap2pg (version 6.0), when I run (Dry Run):
ldap2pg -v 5 -c ldap2pg.yml
I got the following verbose information and end with this fatal error, may I know is that I have to provide password in my ldap.conf or in any .pgpass file? Or this error is related to any missing or wrong configuration?
Note: We have '.pgpass' and in use to connect the PostgreSQL database running on the same server, through psql to connect database with the '.pgpass' file.

Output:
08:54:25 INFO Starting ldap2pg version=v6.0 runtime=go1.20.5 commit=023e6933
08:54:25 INFO Using YAML configuration file. path=ldap2pg.yml
08:54:25 DEBUG Loading YAML configuration.
08:54:25 DEBUG Dumping normalized YAML to stderr.
...
08:54:25 INFO Running as superuser. user=postgres super=true server="PostgreSQL 15.4" cluster="" database=postgres
08:54:25 DEBUG Fallback owner configured. role=postgres
08:54:25 DEBUG Inspecting roles blacklist.
08:54:25 DEBUG Opening Postgres global connection. database=postgres
08:54:25 DEBUG Reading values from YAML.
08:54:25 DEBUG Roles blacklist loaded. patterns="[postgres pg_*]"
08:54:25 DEBUG Found LDAP configuration file. path=/etc/ldap/ldap.conf
08:54:25 DEBUG Ignoring configuration file. path="home dir"/ldaprc err="stat "home dir"/ldaprc: no such file or directory"
08:54:25 DEBUG Ignoring configuration file. path="home dir"/.ldaprc err="stat "home dir"/.ldaprc: no such file or directory"
08:54:25 DEBUG Read LDAP option. key=URI value=ldaps://"our ldap server" origin=/etc/ldap/ldap.conf
08:54:25 DEBUG Read LDAP option. key=TLS_REQCERT value=try origin=default
08:54:25 DEBUG Read LDAP option. key=NETWORK_TIMEOUT value=30 origin=default
08:54:25 DEBUG LDAP dial. uri=ldaps://"our ldap server"
08:54:25 DEBUG Read LDAP option. key=TIMEOUT value=30 origin=default
08:54:25 DEBUG Read LDAP option. key=BINDDN value=""our bind dn" origin=/etc/ldap/ldap.conf
08:54:25 DEBUG LDAP simple bind. binddn="our bind dn"
08:54:25 DEBUG Closing Postgres global connection. database=postgres
08:54:25 ERROR Fatal error. err="LDAP Result Code 206 "Empty password not allowed by the client": ldap: empty password not allowed by the client"

[bersace]

How do you configure LDAPPASSWORD ? I don't see .env loading. Do you still have top level ldap section in YAML ?