An admin user tries to activate/reactivate a Vault User but cannot perform the action, receiving the following error message:
An error occurred while performing the action: User does not have sufficient privileges to perform the action.
The admin user does not have all the permissions that the target user has.
In order to make a Vault user active/inactive, the user doing the action must have all permissions that the the target user has.
Vault Help Documentation: N/A