Following error detected when restart zimbra.

[root@mail]$ zmcontrol start
Starting ldap...Done.
Unable to determine enabled services from ldap.
Enabled services read from cache. Service list may be inaccurate.
Starting logger...Failed.
Starting logswatch...ERROR: service.FAILURE (system failure: ZimbraLdapContext) (cause: PKIX path building failed: unable to find valid certification path to requested target)
zimbra logger service is not enabled! failed.

The usual reason for this error is expired SSL certificate..
This error usually happens if your SSL certificate has expired. There are two solutions for this problem.

Solution 1 – Renew the certificate and deploy it –

[root@mail]$ /opt/zimbra/bin/zmcertmgr deploycrt comm /opt/zimbra/ssl/zimbra/commercial/your_new_ssl.crt /path/to/ca_bundle.crt

Solution 2 – Self Generate the Cert –

[root@mail]$ su - zimbra -c 'zmcontrol stop'
[root@mail]$ rm -rf /opt/zimbra/ssl/*
[root@mail]$ rm -rf /opt/zimbra/ssl/.rnd
[root@mail]$ /opt/zimbra/java/bin/keytool -delete -alias my_ca -keystore /opt/zimbra/java/jre/lib/security/cacerts -storepass changeit
[root@mail]$ /opt/zimbra/java/bin/keytool -delete -alias jetty -keystore /opt/zimbra/mailboxd/etc/keystore -storepass `su - zimbra -c 'zmlocalconfig -s -m nokey mailboxd_keystore_password'`

In order to get the cert active more then 365(default), need to edit /opt/zimbra/bin/zmcertmgr file
Find validation_days=365 and change to validation_days=3650
And save /opt/zimbra/bin/zmcertmgr

[root@mail]$ /opt/zimbra/bin/zmcertmgr createca -new
[root@mail]$ /opt/zimbra/bin/zmcertmgr deployca -localonly
[root@mail]$ /opt/zimbra/bin/zmcertmgr createcrt self -new
[root@mail]$ /opt/zimbra/bin/zmcertmgr deploycrt self

[root@mail]$ su - zimbra -c 'zmcontrol start'

[root@mail]$ /opt/zimbra/bin/zmcertmgr deploycrt self
[root@mail]$ /opt/zimbra/bin/zmcertmgr deployca

[root@mail]$ su - zimbra -c 'zmupdateauthkeys'
[root@mail]$ /opt/zimbra/bin/zmcertmgr viewdeployedcrt