diff --git a/executor/set_test.go b/executor/set_test.go
index 1633c805b09f5..523247bc08dfa 100644
--- a/executor/set_test.go
+++ b/executor/set_test.go
@@ -298,12 +298,12 @@ func (s *testSuite2) TestSetVar(c *C) {
 
 	// test skip isolation level check: error
 	_, err = tk.Exec("SET SESSION TRANSACTION ISOLATION LEVEL SERIALIZABLE")
-	c.Assert(terror.ErrorEqual(err, variable.ErrUnsupportedValueForVar), IsTrue, Commentf("err %v", err))
+	c.Assert(terror.ErrorEqual(err, variable.ErrUnsupportedIsolationLevel), IsTrue, Commentf("err %v", err))
 	tk.MustQuery("select @@session.tx_isolation").Check(testkit.Rows("READ-COMMITTED"))
 	tk.MustQuery("select @@session.transaction_isolation").Check(testkit.Rows("READ-COMMITTED"))
 
 	_, err = tk.Exec("SET GLOBAL TRANSACTION ISOLATION LEVEL SERIALIZABLE")
-	c.Assert(terror.ErrorEqual(err, variable.ErrUnsupportedValueForVar), IsTrue, Commentf("err %v", err))
+	c.Assert(terror.ErrorEqual(err, variable.ErrUnsupportedIsolationLevel), IsTrue, Commentf("err %v", err))
 	tk.MustQuery("select @@global.tx_isolation").Check(testkit.Rows("READ-COMMITTED"))
 	tk.MustQuery("select @@global.transaction_isolation").Check(testkit.Rows("READ-COMMITTED"))
 
@@ -312,8 +312,8 @@ func (s *testSuite2) TestSetVar(c *C) {
 	tk.MustExec("SET SESSION tidb_skip_isolation_level_check = 1")
 	tk.MustExec("SET SESSION TRANSACTION ISOLATION LEVEL SERIALIZABLE")
 	tk.MustQuery("show warnings").Check(testkit.Rows(
-		"Warning 1105 variable 'tx_isolation' does not yet support value: SERIALIZABLE",
-		"Warning 1105 variable 'transaction_isolation' does not yet support value: SERIALIZABLE"))
+		"Warning 1105 The isolation level 'SERIALIZABLE' is not supported. Set tidb_skip_isolation_level_check=1 to skip this error",
+		"Warning 1105 The isolation level 'SERIALIZABLE' is not supported. Set tidb_skip_isolation_level_check=1 to skip this error"))
 	tk.MustQuery("select @@session.tx_isolation").Check(testkit.Rows("SERIALIZABLE"))
 	tk.MustQuery("select @@session.transaction_isolation").Check(testkit.Rows("SERIALIZABLE"))
 
@@ -322,8 +322,8 @@ func (s *testSuite2) TestSetVar(c *C) {
 	tk.MustExec("SET SESSION tidb_skip_isolation_level_check = 1")
 	tk.MustExec("SET GLOBAL TRANSACTION ISOLATION LEVEL READ UNCOMMITTED")
 	tk.MustQuery("show warnings").Check(testkit.Rows(
-		"Warning 1105 variable 'tx_isolation' does not yet support value: READ-UNCOMMITTED",
-		"Warning 1105 variable 'transaction_isolation' does not yet support value: READ-UNCOMMITTED"))
+		"Warning 1105 The isolation level 'READ-UNCOMMITTED' is not supported. Set tidb_skip_isolation_level_check=1 to skip this error",
+		"Warning 1105 The isolation level 'READ-UNCOMMITTED' is not supported. Set tidb_skip_isolation_level_check=1 to skip this error"))
 	tk.MustQuery("select @@global.tx_isolation").Check(testkit.Rows("READ-UNCOMMITTED"))
 	tk.MustQuery("select @@global.transaction_isolation").Check(testkit.Rows("READ-UNCOMMITTED"))
 
diff --git a/sessionctx/variable/session.go b/sessionctx/variable/session.go
index 9673ace21b665..15b45dbb5ff11 100644
--- a/sessionctx/variable/session.go
+++ b/sessionctx/variable/session.go
@@ -604,7 +604,7 @@ func (s *SessionVars) SetSystemVar(name string, val string) error {
 		switch val {
 		case "SERIALIZABLE", "READ-UNCOMMITTED":
 			skipIsolationLevelCheck, err := GetSessionSystemVar(s, TiDBSkipIsolationLevelCheck)
-			returnErr := ErrUnsupportedValueForVar.GenWithStackByArgs(name, val)
+			returnErr := ErrUnsupportedIsolationLevel.GenWithStackByArgs(val)
 			if err != nil {
 				returnErr = err
 			}
diff --git a/sessionctx/variable/sysvar.go b/sessionctx/variable/sysvar.go
index 841f7c0b5ca46..5d705b8cf50e8 100644
--- a/sessionctx/variable/sysvar.go
+++ b/sessionctx/variable/sysvar.go
@@ -85,6 +85,7 @@ var (
 	ErrTruncatedWrongValue         = terror.ClassVariable.New(CodeTruncatedWrongValue, mysql.MySQLErrName[mysql.ErrTruncatedWrongValue])
 	ErrMaxPreparedStmtCountReached = terror.ClassVariable.New(CodeMaxPreparedStmtCountReached, mysql.MySQLErrName[mysql.ErrMaxPreparedStmtCountReached])
 	ErrUnsupportedValueForVar      = terror.ClassVariable.New(CodeUnknownStatusVar, "variable '%s' does not yet support value: %s")
+	ErrUnsupportedIsolationLevel   = terror.ClassVariable.New(CodeUnknownStatusVar, "The isolation level '%s' is not supported. Set tidb_skip_isolation_level_check=1 to skip this error")
 )
 
 func init() {
diff --git a/sessionctx/variable/varsutil.go b/sessionctx/variable/varsutil.go
index 5b61d0c3c1211..e58b245321ad9 100644
--- a/sessionctx/variable/varsutil.go
+++ b/sessionctx/variable/varsutil.go
@@ -430,7 +430,7 @@ func ValidateSetSystemVar(vars *SessionVars, name string, value string) (string,
 		switch upVal {
 		case "SERIALIZABLE", "READ-UNCOMMITTED":
 			skipIsolationLevelCheck, err := GetSessionSystemVar(vars, TiDBSkipIsolationLevelCheck)
-			returnErr := ErrUnsupportedValueForVar.GenWithStackByArgs(name, value)
+			returnErr := ErrUnsupportedIsolationLevel.GenWithStackByArgs(value)
 			if err != nil {
 				returnErr = err
 			}