Symptoms

Client event notification does not work with the following error:

24149 The User properties are not available when the plan option on the activity is set to 'Plan Just Once'

Error message can be found in process error profiles and in ClientRecorder table.
 

Diagnoses

Once you located specific error details you can see root cause of the issue in error message text itself: you are trying to use user properties (specifically email) while using activity destination planning option configured as 'Plan Just Once'.

User properties depicted below (Name, Display Name, Email, Description, Label, FQN, Manager) can not be used when the destination planning option is set to Plan just once (Default).

Changing the destination planning option to Plan Per Destination will resolve the error.
 

Resolution

Issue can be resolved by changing the destination planning options to Plan Per Destination.