A user equipment (UE) device receives, from base station providing a source cell, a conditional handover command identifying a target frequency on a target cell for conditional handover. After determining that conditions have been met for the conditional handover, the UE device observes the target frequency. If the target frequency is occupied, the UE device transmits, to the serving base station, an indication that the target frequency is unavailable for the conditional handover. The indication may include, or be transmitted with, a measurement report.