fix: detect legacy installations with empty schema version

store/migrator.go

@@ -84,14 +84,10 @@ func shouldApplyMigration(fileVersion, currentDBVersion, targetVersion string) b
 // validateMigrationFileName checks if a migration file follows the expected naming convention.
 // Expected format: "NN__description.sql" where NN is a zero-padded number.
 func validateMigrationFileName(filename string) error {
-	if !strings.Contains(filename, MigrateFileNameSplit) {
-		return errors.Errorf("invalid migration filename format (missing %s): %s", MigrateFileNameSplit, filename)
-	}
-	parts := strings.Split(filename, MigrateFileNameSplit)
+	parts := strings.SplitN(filename, MigrateFileNameSplit, 2)
 	if len(parts) < 2 {
-		return errors.Errorf("invalid migration filename format: %s", filename)
+		return errors.Errorf("invalid migration filename format (missing %s): %s", MigrateFileNameSplit, filename)
 	}
-	// Check if first part is a number
 	if _, err := strconv.Atoi(parts[0]); err != nil {
 		return errors.Errorf("migration filename must start with a number: %s", filename)
 	}
@@ -122,7 +118,7 @@ func (s *Store) Migrate(ctx context.Context) error {
 		)
 		return errors.Errorf("cannot downgrade schema version from %s to %s", instanceBasicSetting.SchemaVersion, currentSchemaVersion)
 	}
-	// Apply migrations if needed (including when schema version is empty)
+	// Apply migrations if needed.
 	if isVersionEmpty(instanceBasicSetting.SchemaVersion) || version.IsVersionGreaterThan(currentSchemaVersion, instanceBasicSetting.SchemaVersion) {
 		if err := s.applyMigrations(ctx, instanceBasicSetting.SchemaVersion, currentSchemaVersion); err != nil {
 			return errors.Wrap(err, "failed to apply migrations")
@@ -254,6 +250,7 @@ func (s *Store) preMigrate(ctx context.Context) error {
 	}
 	return nil
 }
+
 func (s *Store) getMigrationBasePath() string {
 	return fmt.Sprintf("migration/%s/", s.profile.Driver)
 }
@@ -370,36 +367,39 @@ func (s *Store) checkMinimumUpgradeVersion(ctx context.Context) error {
 	if err != nil {
 		return errors.Wrap(err, "failed to get instance basic setting")
 	}
-
 	schemaVersion := instanceBasicSetting.SchemaVersion
 
-	// If schema version is >= 0.22.0, the installation is up-to-date
+	// Modern installation: nothing to check.
 	if !isVersionEmpty(schemaVersion) && version.IsVersionGreaterOrEqualThan(schemaVersion, "0.22.0") {
 		return nil
 	}
 
-	// If schema version is set but < 0.22.0, this is an old installation
-	if !isVersionEmpty(schemaVersion) && !version.IsVersionGreaterOrEqualThan(schemaVersion, "0.22.0") {
-		currentVersion, _ := s.GetCurrentSchemaVersion()
-
-		return errors.Errorf(
-			"Your Memos installation is too old to upgrade directly.\n\n"+
-				"Your current version: %s\n"+
-				"Target version: %s\n"+
-				"Minimum required: v0.22.0 (May 2024)\n\n"+
-				"Upgrade path:\n"+
-				"1. First upgrade to v0.25.3: https://github.com/usememos/memos/releases/tag/v0.25.3\n"+
-				"2. Start the server and verify it works\n"+
-				"3. Then upgrade to the latest version\n\n"+
-				"This is required because schema version tracking was moved from migration_history\n"+
-				"to system_setting in v0.22.0. The intermediate upgrade handles this migration safely.",
-			schemaVersion,
-			currentVersion,
-		)
+	// Schema version is empty for fresh installs too, but preMigrate sets it before we get here.
+	// So empty schema version on an initialized DB means a pre-v0.22 legacy installation.
+	if isVersionEmpty(schemaVersion) {
+		initialized, err := s.driver.IsInitialized(ctx)
+		if err != nil {
+			return errors.Wrap(err, "failed to check if database is initialized")
+		}
+		if !initialized {
+			return nil
+		}
 	}
 
-	// Schema version is empty - this is either a fresh install or corrupted installation
-	// Fresh installs will have schema version set immediately after LATEST.sql is applied
-	// So this should not be an issue in normal operation
-	return nil
+	// schemaVersion is either set but < 0.22.0, or empty on an initialized (legacy) DB.
+	currentVersion, _ := s.GetCurrentSchemaVersion()
+	return errors.Errorf(
+		"Your Memos installation is too old to upgrade directly.\n\n"+
+			"Your current version: %s\n"+
+			"Target version: %s\n"+
+			"Minimum required: v0.22.0 (May 2024)\n\n"+
+			"Upgrade path:\n"+
+			"1. First upgrade to v0.25.3: https://github.com/usememos/memos/releases/tag/v0.25.3\n"+
+			"2. Start the server and verify it works\n"+
+			"3. Then upgrade to the latest version\n\n"+
+			"This is required because schema version tracking was moved from migration_history\n"+
+			"to system_setting in v0.22.0. The intermediate upgrade handles this migration safely.",
+		schemaVersion,
+		currentVersion,
+	)
 }