diff --git a/homeassistant/components/local_calendar/calendar.py b/homeassistant/components/local_calendar/calendar.py
index 423be8143b8..c8807d40cc1 100644
--- a/homeassistant/components/local_calendar/calendar.py
+++ b/homeassistant/components/local_calendar/calendar.py
@@ -129,7 +129,7 @@ class LocalCalendarEntity(CalendarEntity):
                 recurrence_range=range_value,
             )
         except EventStoreError as err:
-            raise HomeAssistantError("Error while deleting event: {err}") from err
+            raise HomeAssistantError(f"Error while deleting event: {err}") from err
         await self._async_store()
         await self.async_update_ha_state(force_refresh=True)
 
@@ -153,7 +153,7 @@ class LocalCalendarEntity(CalendarEntity):
                 recurrence_range=range_value,
             )
         except EventStoreError as err:
-            raise HomeAssistantError("Error while updating event: {err}") from err
+            raise HomeAssistantError(f"Error while updating event: {err}") from err
         await self._async_store()
         await self.async_update_ha_state(force_refresh=True)