diff --git a/cmd/moco-agent/cmd/root.go b/cmd/moco-agent/cmd/root.go
index 14489d5..09be0e3 100644
--- a/cmd/moco-agent/cmd/root.go
+++ b/cmd/moco-agent/cmd/root.go
@@ -259,7 +259,7 @@ func initializeMySQLForMOCO(ctx context.Context, socketPath string, logger logr.
 		if err == nil {
 			break
 		}
-		if server.IsAccessDenied(err) {
+		if server.UserNotExists(err) {
 			// There is no passwordless 'root'@'localhost' account.
 			// It means the initialization has been completed.
 			return nil
diff --git a/server/connect.go b/server/connect.go
index 413413d..557a268 100644
--- a/server/connect.go
+++ b/server/connect.go
@@ -53,9 +53,15 @@ func GetMySQLConnLocalSocket(user, password, socket string) (*sqlx.DB, error) {
 	return db, nil
 }
 
-func IsAccessDenied(err error) bool {
+func UserNotExists(err error) bool {
+	// For security reason, error messages are randomly output when a user does not exist.
+	//   https://github.com/mysql/mysql-server/commit/b40001faf6229dca668c9d03ba75c451f999c9f5
+	// This function assumes the user does not exist when the following message is output:
+	//   ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
+	//   ERROR 1524 (HY000): Plugin 'mysql_native_password' is not loaded
+	codes := []int{1045, 1524}
 	var merr *mysql.MySQLError
-	if errors.As(err, &merr) && merr.Number == 1045 {
+	if errors.As(err, &merr) && contains(codes, merr.Number) {
 		return true
 	}