As reported in #1994242: Drupal to LDAP sync not happening.. → users have issues when configuring a valid mapping to LDAP. While we cannot fully anticipate a valid mapping configuration for their environment (e.g. what the valid objectClass attributes are needed), there should be no situation where the DN is not required.
One solution would be to provide one extra mapping up-front as a required field which the user would have fill out. Alternatively, but more obscure, would be deriving the DN from user data tables after an initial provisioning event.
Closed: won't fix
4.0
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