The error “Members can’t remove themselves from security groups. Please set the group to Closed for requests to leave.” when editing a distribution group.

Scenario: When editing the managers of a distribution group, this error is displayed:

Members can’t remove themselves from security groups. Please set the group to Closed for requests to leave.

Resolution: Set the MemberDepartRestriction to closed for that distribution group.

set-distributiongroup  <alias of group> -memberdepartrestriction closed