golangci/golangci-lint · error

TOML decode file %s: %w

Error message

TOML decode file %s: %w

What it means

parser.Decode wraps errors from toml.NewDecoder(file).Decode(&data) when a .toml configuration file cannot be parsed. It means the TOML content is syntactically invalid, so the migration/decode step cannot read the configuration.

Source

Thrown at pkg/commands/internal/migrate/parser/parser.go:36

	Name() string
}

// Decode decodes a file into data.
// The choice of the decoder is based on the file extension.
func Decode(file File, data any) error {
	ext := filepath.Ext(file.Name())

	switch strings.ToLower(ext) {
	case ".yaml", ".yml", ".json":
		err := yaml.NewDecoder(file).Decode(data)
		if err != nil && !errors.Is(err, io.EOF) {
			return fmt.Errorf("YAML decode file %s: %w", file.Name(), err)
		}

	case ".toml":
		err := toml.NewDecoder(file).Decode(&data)
		if err != nil {
			return fmt.Errorf("TOML decode file %s: %w", file.Name(), err)
		}

	default:
		return fmt.Errorf("unsupported file type: %s", ext)
	}

	return nil
}

// Encode encodes data into a file.
// The choice of the encoder is based on the file extension.
func Encode(data any, dstFile File) error {
	ext := filepath.Ext(dstFile.Name())

	switch strings.ToLower(ext) {
	case ".yml", ".yaml":
		encoder := yaml.NewEncoder(dstFile)
		encoder.SetIndent(2)

View on GitHub (pinned to ed7a235d2d)

Solutions

1. Fix the TOML syntax at the reported location (the wrapped error names line/column).
2. Validate with a TOML linter such as `tomll` or an online TOML parser.
3. Quote all string values and ensure table headers like [linters] are properly declared.
4. Convert the config to YAML/JSON if TOML editing keeps causing issues.

Example fix

// before (.golangci.toml)
[linters]
enable = gocritic
// after
[linters]
enable = ["gocritic"]

content, err := os.ReadFile(cfgPath)
if err != nil { return err }
if !toml.Validate(content) { return errors.New("invalid TOML in " + cfgPath) }

if err := parser.Decode(f, &data); err != nil {
    if strings.Contains(err.Error(), "TOML decode") {
        // surface line/column from wrapped toml error
    }
    return err
}

When it happens

Trigger: Calling Decode on a .toml file containing invalid TOML: unterminated strings, missing [section] brackets, duplicate keys within a table, or invalid key/value syntax.

Common situations: Hand-edited .golangci.toml with typos, copy-pasted TOML missing quotes around string values, or a file corrupted by automated tooling.

Related errors

• YAML decode file %s: %w
• [%s] TOML decode: %w
• hash plugin directory: %w
• file %s not found: %w
• file %s open: %w

AI-assisted analysis of golangci/golangci-lint@ed7a235d2d (2026-09-02). Data as JSON: /api/errors/9f80ea7b31dbdd6b. Report an issue: GitHub.