diff --git a/table/tables/tables.go b/table/tables/tables.go
index 014a11f8fbb0e..2d702b79b5c0a 100644
--- a/table/tables/tables.go
+++ b/table/tables/tables.go
@@ -481,9 +481,12 @@ func (t *TableCommon) UpdateRecord(ctx context.Context, sctx sessionctx.Context,
 	})
 
 	if t.shouldAssert(sctx) {
-		if err = txn.SetAssertion(key, kv.SetAssertExist); err != nil {
-			return err
-		}
+		err = txn.SetAssertion(key, kv.SetAssertExist)
+	} else {
+		err = txn.SetAssertion(key, kv.SetAssertUnknown)
+	}
+	if err != nil {
+		return err
 	}
 
 	if err = injectMutationError(t, txn, sh); err != nil {
@@ -1346,9 +1349,11 @@ func (t *TableCommon) removeRowData(ctx sessionctx.Context, h kv.Handle) error {
 	})
 	if t.shouldAssert(ctx) {
 		err = txn.SetAssertion(key, kv.SetAssertExist)
-		if err != nil {
-			return err
-		}
+	} else {
+		err = txn.SetAssertion(key, kv.SetAssertUnknown)
+	}
+	if err != nil {
+		return err
 	}
 	return txn.Delete(key)
 }
diff --git a/tests/realtikvtest/sessiontest/session_fail_test.go b/tests/realtikvtest/sessiontest/session_fail_test.go
index a3df51be821c0..ad986c5386350 100644
--- a/tests/realtikvtest/sessiontest/session_fail_test.go
+++ b/tests/realtikvtest/sessiontest/session_fail_test.go
@@ -203,3 +203,24 @@ func TestKill(t *testing.T) {
 	tk := testkit.NewTestKit(t, store)
 	tk.MustExec("kill connection_id();")
 }
+
+func TestIssue42426(t *testing.T) {
+	store := realtikvtest.CreateMockStoreAndSetup(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("CREATE TABLE `sbtest1` (" +
+		"`id` bigint(20) NOT NULL AUTO_INCREMENT," +
+		"`k` int(11) NOT NULL DEFAULT '0'," +
+		"`c` char(120) NOT NULL DEFAULT ''," +
+		"`pad` char(60) NOT NULL DEFAULT ''," +
+		"PRIMARY KEY (`id`) /*T![clustered_index] CLUSTERED */," +
+		"KEY `k_1` (`k`)" +
+		") PARTITION BY RANGE (`id`)" +
+		"(PARTITION `pnew` VALUES LESS THAN (10000000)," +
+		"PARTITION `p5` VALUES LESS THAN (MAXVALUE));")
+	tk.MustExec(`INSERT INTO sbtest1 (id, k, c, pad) VALUES (502571, 499449, "init", "val");`)
+	tk.MustExec(`BEGIN`)
+	tk.MustExec(`DELETE FROM sbtest1 WHERE id=502571;`)
+	tk.MustExec(`INSERT INTO sbtest1 (id, k, c, pad) VALUES (502571, 499449, "abc", "def");`)
+	tk.MustExec(`COMMIT;`)
+}