rguerrero@datamirror.com writes:

ldap_extended_operation(ld = (nil), reqoid = "1.3.6.1.4.1.1466.20037", reqdata = (nil), sctrls = (nil), cctrls = ??, msgidp = 0x2ff18cd4), line 62 in "extended.c" ldap_start_tls(ld = ??, serverctrls = ??, clientctrls = ??, msgidp = ??), line 1859 in "tls.c" do_start_tls(session = 0xf027b7f0), line 1343 in "ldap-nss.c"

Looks like an ldap-nss.c problem to me, not an OpenLDAP problem. An uninitialized (or destroyed but not zeroed) LDAP*, perhaps? Look at the value of *session, in particular session->ls_conn, in the do_start_tls() frame.