The tmnxSubCupsUpIfCreationFailed notification is sent when an attempt of the Control and User Plane Separation (CUPS) User Plane to create an interface has failed. [CAUSE] A failure occurs while the CUPS User Plane tries to create an interface. The object tmnxSubAdditionalInfo provides more information about the failure. [EFFECT] The interface is not created. It is impossible to create the SAPs that would be associated with it. Subscriber sessions that need these SAPs cannot become operational. [RECOVERY] The recovery action depends on the root cause of the failure.