Quoting Jaap Winius <jwinius@xxxxxxx>:
slapd[1668]: GSSAPI Error: Unspecified GSS failure. \ Minor code may provide more information \ (Server ldap/localhost@xxxxxxxxxxx not found in Kerberos database)
Maybe this is really a slapd issue, particularly if it's job here is to interpret the value of the KRB5_KTNAME variable and then pass that (or perhaps even the name of the Kerberos principal) on to the SASL/GSSAPI functions. Well, either that or the latter aren't processing the name of the file or principal properly.
Cheers, Jaap