OpenLDAP：Failed to start OpenLDAP Server Daemon.

Job for slapd.service failed because the control process exited with error code. See "systemctl status slapd.service" and "journalctl -xe" for details.

[root@VM_0_9_centos ~]# systemctl status slapd.service
● slapd.service - OpenLDAP Server Daemon
   Loaded: loaded (/usr/lib/systemd/system/slapd.service; enabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Sun 2020-06-21 22:09:42 CST; 1min 18s ago
     Docs: man:slapd
           man:slapd-config
           man:slapd-hdb
           man:slapd-mdb
           file:///usr/share/doc/openldap-servers/guide.html
  Process: 29861 ExecStart=/usr/sbin/slapd -u ldap -h ${SLAPD_URLS} $SLAPD_OPTIONS (code=exited, status=1/FAILURE)
  Process: 29828 ExecStartPre=/usr/libexec/openldap/check-config.sh (code=exited, status=0/SUCCESS)

Jun 21 22:09:41 VM_0_9_centos runuser[29851]: pam_unix(runuser:session): session opened for user lda... d=0)
Jun 21 22:09:41 VM_0_9_centos runuser[29853]: pam_unix(runuser:session): session opened for user lda... d=0)
Jun 21 22:09:41 VM_0_9_centos runuser[29855]: pam_unix(runuser:session): session opened for user lda... d=0)
Jun 21 22:09:41 VM_0_9_centos runuser[29857]: pam_unix(runuser:session): session opened for user lda... d=0)
Jun 21 22:09:41 VM_0_9_centos runuser[29859]: pam_unix(runuser:session): session opened for user lda... d=0)
Jun 21 22:09:42 VM_0_9_centos slapd[29861]: @(#) $OpenLDAP: slapd 2.4.44 (Jan 29 2019 17:42:45) $
                                                    mockbuild@x86-01.bsys.centos.org:/builddir/build... lapd
Jun 21 22:09:42 VM_0_9_centos systemd[1]: slapd.service: control process exited, code=exited status=1
Jun 21 22:09:42 VM_0_9_centos systemd[1]: Failed to start OpenLDAP Server Daemon.
Jun 21 22:09:42 VM_0_9_centos systemd[1]: Unit slapd.service entered failed state.
Jun 21 22:09:42 VM_0_9_centos systemd[1]: slapd.service failed.
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