Apparatus and methods are provided for handover robustness. In novel aspect, the UE receives a conditional handover (CHO) command from a source gNB containing a set of candidate cells with corresponding triggering conditions; detects a handover conditions for a target gNB belonging to the set of candidate cells; and performs HO procedure towards the target gNB. In one embodiment, the conditional HO command further configures a validity timer that controls a validity of handover conditions for the set of candidate cells. The validity timer is started upon receiving the conditional HO command, the validity timer is stopped upon detecting at least one events comprising a handover condition is met and a normal handover command is received, and the conditional HO command is set to be invalid upon the expiration of the validity timer.