Could not authenticate you from Ldapmain because "Ssl connect returned=1 errno=0 state=error: certificate verify failed".

our gitlab version is GitLab Community Edition 10.0.2 when using LDAP auth, it return error

Could not authenticate you from Ldapmain because "Ssl connect returned=1 errno=0 state=error: certificate verify failed".

and here are the outputs of gitlab-rake gitlab:check the LDAP check does not pass.

Checking LDAP ...

Server: ldapmain
rake aborted!
Net::LDAP::Error: SSL_connect returned=1 errno=0 state=error: certificate verify failed
/opt/gitlab/embedded/service/gitlab-rails/lib/gitlab/ldap/adapter.rb:7:in `open'
/opt/gitlab/embedded/service/gitlab-rails/lib/tasks/gitlab/check.rake:356:in `block in check_ldap'
/opt/gitlab/embedded/service/gitlab-rails/lib/tasks/gitlab/check.rake:352:in `each'
/opt/gitlab/embedded/service/gitlab-rails/lib/tasks/gitlab/check.rake:352:in `check_ldap'
/opt/gitlab/embedded/service/gitlab-rails/lib/tasks/gitlab/check.rake:341:in `block (3 levels) in <top (required)>'
/opt/gitlab/embedded/bin/bundle:23:in `load'
/opt/gitlab/embedded/bin/bundle:23:in `<main>'
Tasks: TOP => gitlab:check => gitlab:ldap:check
(See full trace by running task with --trace)