diff --git a/SAS/TMSS/backend/src/tmss/tmssapp/populate.py b/SAS/TMSS/backend/src/tmss/tmssapp/populate.py
index e7c757539af412c484ff799f7bb48ad9fe8b4056..9132ea1bf43366ac65cb03a3876d21be83482721 100644
--- a/SAS/TMSS/backend/src/tmss/tmssapp/populate.py
+++ b/SAS/TMSS/backend/src/tmss/tmssapp/populate.py
@@ -160,6 +160,8 @@ def populate_subtask_allowed_state_transitions(apps, schema_editor):
         SubtaskAllowedStateTransitions(old_state=SCHEDULING, new_state=SCHEDULED),
         SubtaskAllowedStateTransitions(old_state=SCHEDULING, new_state=UNSCHEDULABLE),
         SubtaskAllowedStateTransitions(old_state=UNSCHEDULABLE, new_state=DEFINED),
+        SubtaskAllowedStateTransitions(old_state=UNSCHEDULABLE, new_state=CANCELLED),
+        SubtaskAllowedStateTransitions(old_state=UNSCHEDULABLE, new_state=ERROR),
         SubtaskAllowedStateTransitions(old_state=SCHEDULED, new_state=STARTING), # this is an odd one, as most (all?) subtasks are queued before execution...
         SubtaskAllowedStateTransitions(old_state=SCHEDULED, new_state=QUEUEING),
         SubtaskAllowedStateTransitions(old_state=SCHEDULED, new_state=UNSCHEDULING),
diff --git a/SAS/TMSS/backend/test/test_utils.py b/SAS/TMSS/backend/test/test_utils.py
index 86ac97ee5d768f26f1ce624b8e9b9c7d18148e0f..9c8fe9aedcbabac601e3d9e8fee0ed30cdd59fdc 100644
--- a/SAS/TMSS/backend/test/test_utils.py
+++ b/SAS/TMSS/backend/test/test_utils.py
@@ -109,6 +109,7 @@ def set_subtask_state_following_allowed_transitions(subtask: typing.Union[Subtas
                                                                                                  SubtaskState.Choices.QUEUEING.value,
                                                                                                  SubtaskState.Choices.STARTING.value,
                                                                                                  SubtaskState.Choices.FINISHING.value,
+                                                                                                 SubtaskState.Choices.UNSCHEDULABLE.value,
                                                                                                  SubtaskState.Choices.CANCELLING.value):
             subtask.state = SubtaskState.objects.get(value=SubtaskState.Choices.ERROR.value)
             subtask.error_reason = 'set_subtask_state_following_allowed_transitions'