diff --git a/engine/apps/schedules/ical_utils.py b/engine/apps/schedules/ical_utils.py
index 8eeacddf..13d0771b 100644
--- a/engine/apps/schedules/ical_utils.py
+++ b/engine/apps/schedules/ical_utils.py
@@ -490,7 +490,12 @@ def get_cached_oncall_users_for_multiple_schedules(schedules: typing.List["OnCal
     for cache_key, oncall_users in cached_results.items():
         schedule_public_primary_key = _get_schedule_public_primary_key_from_schedule_oncall_users_cache_key(cache_key)
         schedule = schedules[schedule_public_primary_key]
-        oncall_users = [users[user_public_primary_key] for user_public_primary_key in oncall_users]
+        oncall_users = [
+            users[user_public_primary_key]
+            for user_public_primary_key in oncall_users
+            # filter out any users that we couldn't find in the database (e.g. deleted)
+            if user_public_primary_key in users
+        ]
 
         results[schedule] = oncall_users
 
diff --git a/engine/apps/schedules/tests/test_ical_utils.py b/engine/apps/schedules/tests/test_ical_utils.py
index 3b6cf517..dd54ec45 100644
--- a/engine/apps/schedules/tests/test_ical_utils.py
+++ b/engine/apps/schedules/tests/test_ical_utils.py
@@ -671,3 +671,12 @@ def test_get_cached_oncall_users_for_multiple_schedules(
         _generate_cache_key(schedule2): [users[2].public_primary_key, users[3].public_primary_key],
         _generate_cache_key(schedule3): [users[4].public_primary_key, users[5].public_primary_key],
     }
+
+    # scenario: user is deleted but still in cache (all schedules are still in cache)
+    users[0].delete()
+    results = get_cached_oncall_users_for_multiple_schedules(schedules)
+    assert results == {
+        schedule1: [users[1]],
+        schedule2: [users[2], users[3]],
+        schedule3: [users[4], users[5]],
+    }