Self signed certificate in certificate chain

I am receiving following error while trying to login using LDAP:

Could not authenticate you from Ldapmain because "Ssl connect returned=1 errno=0 state=error: certificate verify failed (self signed certificate in certificate chain)".

Here is the important part of /etc/gitlab/gitlab.rb

    main: # 'main' is the GitLab 'provider ID' of this LDAP server
         label: 'LDAP'
         host: 'localhost'
         port: 636
         uid: 'uid'
         method: 'ssl' # "tls" or "ssl" or "plain"
         encryption: 'simple_tls'
         bind_dn: 'cn=ldap,dc=develop,dc=***,dc=***'
         password: '***'
         verify_certificates: false
         active_directory: false
         allow_username_or_email_login: false
         block_auto_created_users: false

And this is the output of sudo gitlab-rake gitlab:check --trace

LDAP authentication... Success
LDAP users with access to your GitLab server (only showing the first 100 results)
	DN: uid=asleem,ou=users,dc=develop,dc=***,dc=***	 uid: asleem
	DN: uid=aladutsenko,ou=users,dc=develop,dc=***,dc=***	 uid: aladutsenko
	DN: uid=nradovanovic,ou=users,dc=develop,dc=***,dc=***	 uid: nradovanovic

Checking LDAP ... Finished

Any help is more than welcome since users (inluding myself) cant login anymore.

Best regards