diff --git a/blazar/status.py b/blazar/status.py
index 24783240..e8d549ee 100644
--- a/blazar/status.py
+++ b/blazar/status.py
@@ -307,8 +307,12 @@ COMBINATIONS = {
     },
     LeaseStatus.DELETING: {
         'reservation': ReservationStatus.ALL,
-        'start_lease': EventStatus.ALL,
-        'end_lease': EventStatus.ALL
+        'start_lease': (EventStatus.UNDONE,
+                        EventStatus.DONE,
+                        EventStatus.ERROR),
+        'end_lease': (EventStatus.UNDONE,
+                      EventStatus.DONE,
+                      EventStatus.ERROR)
     },
     LeaseStatus.UPDATING: {
         'reservation': ReservationStatus.ALL,
diff --git a/releasenotes/notes/prevent-delete-during-events-c206a8f0a116798c.yaml b/releasenotes/notes/prevent-delete-during-events-c206a8f0a116798c.yaml
new file mode 100644
index 00000000..50317a26
--- /dev/null
+++ b/releasenotes/notes/prevent-delete-during-events-c206a8f0a116798c.yaml
@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    Blazar now prevents leases from being deleted while their start_lease or
+    end_lease events are in progress, to avoid concurrently accessing shared
+    objects. For more details, see `bug 1791741
+    <https://bugs.launchpad.net/blazar/+bug/1791741>`_.