--- comm-1.9.1/calendar/providers/storage/calStorageUpgrade.jsm	2009-12-05 02:53:54.000000000 +0100
+++ comm-1.9.1/calendar/providers/storage/calStorageUpgrade.jsm-gil	2009-12-21 01:03:19.000000000 +0100
@@ -1141,10 +1141,17 @@
                 // then swallowing
                 // the error is ok too since the cols will already be added in
                 // v16.
-                db.createStatement("SELECT recurrence_id_tz," +
+                // Stepping this statement will fail if the columns don't exist.
+                // We don't use the delegate here since it would show an error to
+                // the user, even through we expect the error. If the db is null,
+                // then swallowing the error is ok too since the cols will
+                // already be added in v16.
+                let stmt = db.createStatement("SELECT recurrence_id_tz," +
                                    "       recurrence_id" +
                                    "  FROM cal_" + tblName +
                                    " LIMIT 1");
+                stmt.step();
+                stmt.finalize();
             } catch (e) {
                 // An error happened, which means the cols don't exist
                 hasColumns = false;