Why Do I Get a TLS Error When Authenticating LDAP Users in Ansible Tower?

Issue

When trying to authenticate LDAP users in Tower, tower.log displays this error:

django_auth_ldap Caught LDAPError while authenticating user@domain: OPERATIONS_ERROR({'info': '00000000: LdapErr: DSID-0C090F86, comment: TLS or SSL already in effect, data 0, v2580', 'desc': 'Operations error'},)

or Free IPA / Red Hat IDM version might throw this:

django_auth_ldap Caught LDAPError while authenticating user@exampl.corp: OPERATIONS_ERROR({'info': 'SSL connection already established.', 'desc': 'Operations error'},)