ldap_error: Net::LDAP::Error, SSL_connect returned=1 errno=0 state=error: certificate verify failed

Hi,

I'm using gitlab-ce docker version 9.4.3-ce.0,

Here's my ldap config in gitlab.rb:

gitlab_rails['ldap_enabled'] = true
gitlab_rails['ldap_servers'] = YAML.load <<-'EOS'
  main: # 'main' is the GitLab 'provider ID' of this LDAP server
    label: 'LDAP'
    host: 'ldap01.demo.com'
    port: 636
    uid: 'uid'
    bind_dn: 'uid=ldapserviceaccount,ou=Users,dc=demo,dc=com'
    password: '123456'
    encryption: 'simple_tls' # "start_tls" or "simple_tls" or "plain"
    verify_certificates: true
    ca_cert: '/etc/gitlab/ldapcacert.crt'
    active_directory: false
    allow_username_or_email_login: false
    block_auto_created_users: false
    base: 'ou=Users,dc=demo,dc=com'
    attributes:
      username: ['uid']
      email:    ['mail']
      name:       'cn'
      first_name: 'givenName'
      last_name:  'sn'
EOS

When I try to login with my ldap account, error pops up here:

Authentication failure! ldap_error: Net::LDAP::Error, SSL_connect returned=1 errno=0 state=error: certificate verify failed

What's the problem here? Do I have to disable "verify_certificates"? Thanks for the help.