diff --git a/meta/autoid/autoid.go b/meta/autoid/autoid.go
index 0b65c84595e13..02188c30935a6 100755
--- a/meta/autoid/autoid.go
+++ b/meta/autoid/autoid.go
@@ -250,7 +250,7 @@ func NewAllocator(store kv.Storage, dbID int64, isUnsigned bool) Allocator {
 	}
 }
 
-//codeInvalidTableID is the code of autoid error.
+// codeInvalidTableID is the code of autoid error.
 const codeInvalidTableID terror.ErrCode = 1
 
 var localSchemaID = int64(math.MaxInt64)
diff --git a/privilege/privileges/errors.go b/privilege/privileges/errors.go
index f4cdca47e41a8..55fbc0a3d3842 100644
--- a/privilege/privileges/errors.go
+++ b/privilege/privileges/errors.go
@@ -20,19 +20,17 @@ import (
 
 // privilege error codes.
 const (
-	codeInvalidPrivilegeType  terror.ErrCode = 1
-	codeInvalidUserNameFormat                = 2
-	codeErrNonexistingGrant                  = mysql.ErrNonexistingGrant
+	codeInvalidPrivilegeType terror.ErrCode = 1
 )
 
 var (
 	errInvalidPrivilegeType = terror.ClassPrivilege.New(codeInvalidPrivilegeType, "unknown privilege type %s")
-	errNonexistingGrant     = terror.ClassPrivilege.New(codeErrNonexistingGrant, mysql.MySQLErrName[mysql.ErrNonexistingGrant])
+	errNonexistingGrant     = terror.ClassPrivilege.New(mysql.ErrNonexistingGrant, mysql.MySQLErrName[mysql.ErrNonexistingGrant])
 )
 
 func init() {
 	privilegeMySQLErrCodes := map[terror.ErrCode]uint16{
-		codeErrNonexistingGrant: mysql.ErrNonexistingGrant,
+		mysql.ErrNonexistingGrant: mysql.ErrNonexistingGrant,
 	}
 	terror.ErrClassToMySQLCodes[terror.ClassPrivilege] = privilegeMySQLErrCodes
 }
diff --git a/server/server.go b/server/server.go
index b83d7b945f43e..7be1097e7c50d 100644
--- a/server/server.go
+++ b/server/server.go
@@ -87,8 +87,8 @@ var (
 	errUnknownFieldType  = terror.ClassServer.New(codeUnknownFieldType, "unknown field type")
 	errInvalidSequence   = terror.ClassServer.New(codeInvalidSequence, "invalid sequence")
 	errInvalidType       = terror.ClassServer.New(codeInvalidType, "invalid type")
-	errNotAllowedCommand = terror.ClassServer.New(codeNotAllowedCommand, "the used command is not allowed with this TiDB version")
-	errAccessDenied      = terror.ClassServer.New(codeAccessDenied, mysql.MySQLErrName[mysql.ErrAccessDenied])
+	errNotAllowedCommand = terror.ClassServer.New(mysql.ErrNotAllowedCommand, mysql.MySQLErrName[mysql.ErrNotAllowedCommand])
+	errAccessDenied      = terror.ClassServer.New(mysql.ErrAccessDenied, mysql.MySQLErrName[mysql.ErrAccessDenied])
 )
 
 // DefaultCapability is the capability of the server when it is created using the default configuration.
@@ -617,21 +617,15 @@ func (s *Server) kickIdleConnection() {
 
 // Server error codes.
 const (
-	codeUnknownFieldType  = 1
-	codeInvalidPayloadLen = 2
-	codeInvalidSequence   = 3
-	codeInvalidType       = 4
-
-	codeNotAllowedCommand   = 1148
-	codeAccessDenied        = mysql.ErrAccessDenied
-	codeMaxExecTimeExceeded = mysql.ErrMaxExecTimeExceeded
+	codeUnknownFieldType = 1
+	codeInvalidSequence  = 3
+	codeInvalidType      = 4
 )
 
 func init() {
 	serverMySQLErrCodes := map[terror.ErrCode]uint16{
-		codeNotAllowedCommand:   mysql.ErrNotAllowedCommand,
-		codeAccessDenied:        mysql.ErrAccessDenied,
-		codeMaxExecTimeExceeded: mysql.ErrMaxExecTimeExceeded,
+		mysql.ErrNotAllowedCommand: mysql.ErrNotAllowedCommand,
+		mysql.ErrAccessDenied:      mysql.ErrAccessDenied,
 	}
 	terror.ErrClassToMySQLCodes[terror.ClassServer] = serverMySQLErrCodes
 }
diff --git a/session/tidb.go b/session/tidb.go
index e50098d669330..a556bfbcbdb2a 100644
--- a/session/tidb.go
+++ b/session/tidb.go
@@ -367,17 +367,12 @@ func ResultSetToStringSlice(ctx context.Context, s Session, rs sqlexec.RecordSet
 
 // Session errors.
 var (
-	ErrForUpdateCantRetry = terror.ClassSession.New(codeForUpdateCantRetry,
-		mysql.MySQLErrName[mysql.ErrForUpdateCantRetry])
-)
-
-const (
-	codeForUpdateCantRetry terror.ErrCode = mysql.ErrForUpdateCantRetry
+	ErrForUpdateCantRetry = terror.ClassSession.New(mysql.ErrForUpdateCantRetry, mysql.MySQLErrName[mysql.ErrForUpdateCantRetry])
 )
 
 func init() {
 	sessionMySQLErrCodes := map[terror.ErrCode]uint16{
-		codeForUpdateCantRetry: mysql.ErrForUpdateCantRetry,
+		mysql.ErrForUpdateCantRetry: mysql.ErrForUpdateCantRetry,
 	}
 	terror.ErrClassToMySQLCodes[terror.ClassSession] = sessionMySQLErrCodes
 }
diff --git a/structure/structure.go b/structure/structure.go
index 3aba2214550a9..b736ec9daf981 100644
--- a/structure/structure.go
+++ b/structure/structure.go
@@ -20,11 +20,9 @@ import (
 
 // structure error codes.
 const (
-	codeInvalidHashKeyFlag   terror.ErrCode = 1
-	codeInvalidHashKeyPrefix terror.ErrCode = 2
-	codeInvalidListIndex     terror.ErrCode = 3
-	codeInvalidListMetaData  terror.ErrCode = 4
-	codeWriteOnSnapshot      terror.ErrCode = 5
+	codeInvalidHashKeyFlag  terror.ErrCode = 1
+	codeInvalidListMetaData terror.ErrCode = 4
+	codeWriteOnSnapshot     terror.ErrCode = 5
 )
 
 var (