Luc MAIGNAN wrote:

I try to upgrade openldap to 2.4.

Which version did you use before?

Generally you should slapcat the whole content of your database(s) and use slapadd to bulk-load it into your new server.

Considering the documentation on my new freshly installed server on which I've restored the slapd.conf of a previous server, I try :

slaptest -f /etc/openldap/slapd.conf -F /etc/openldap/slapd.d

Why are you doing this? You can still use your static configuration file /etc/openldap/slapd.conf with recent OpenLDAP 2.4.31.

This gives me this issue :

bdb_db_open: database "dc=domain,dc=com": db_open(/var/lib/ldap/id2entry.bdb) failed: No such file or directory (2). backend_startup_one (type=bdb, suffix="dc=domain,dc=com"): bi_db_open failed! (2)

This clearly says that something's seriously wrong - probably ownership/permissions or the directoy /var/lib/ldap is missing.

I've found on internet that I can safely ignore this,

The "internet" is not always right.

Ciao, Michael.