golang/go · error

import path contains invalid UTF-8 sequence: %q

Error message

import path contains invalid UTF-8 sequence: %q

What it means

Returned by checkImportPath when iterating the path's runes encounters utf8.RuneError, which signals invalid UTF-8 (either a lone continuation byte or an overlong/invalid sequence). Go import paths must be valid UTF-8.

Source

Thrown at src/cmd/compile/internal/noder/import.go:320

func checkImportPath(path string, allowSpace bool) error {
	if path == "" {
		return errors.New("import path is empty")
	}

	if strings.Contains(path, "\x00") {
		return errors.New("import path contains NUL")
	}

	for ri := range base.ReservedImports {
		if path == ri {
			return fmt.Errorf("import path %q is reserved and cannot be used", path)
		}
	}

	for _, r := range path {
		switch {
		case r == utf8.RuneError:
			return fmt.Errorf("import path contains invalid UTF-8 sequence: %q", path)
		case r < 0x20 || r == 0x7f:
			return fmt.Errorf("import path contains control character: %q", path)
		case r == '\\':
			return fmt.Errorf("import path contains backslash; use slash: %q", path)
		case !allowSpace && unicode.IsSpace(r):
			return fmt.Errorf("import path contains space character: %q", path)
		case strings.ContainsRune("!\"#$%&'()*,:;<=>?[]^`{|}", r):
			return fmt.Errorf("import path contains invalid character '%c': %q", r, path)
		}
	}

	return nil
}

View on GitHub (pinned to b6b368adc5)

Solutions

1. Re-encode the import path as UTF-8 (iconv or your editor's encoding setting).
2. Retype the import line by hand to drop stray bytes.
3. Validate with a UTF-8 checker (e.g. printf %s path | iconv -f utf-8 -t utf-8).

if !utf8.ValidString(path) {
    return fmt.Errorf("import path is not valid UTF-8: %q", path)
}

When it happens

Trigger: An import path string contains bytes that do not decode as valid UTF-8; the for-range loop yields utf8.RuneError and the error names the whole path.

Common situations: Pasting an import path with mojibake or non-UTF-8 bytes; a filesystem-derived path encoded in Latin-1 or GBK; binary corruption of a source file's import line.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• import path %q is reserved and cannot be used
• import path contains control character: %q
• import path contains backslash; use slash: %q
• import path contains space character: %q
• import path contains invalid character '%c': %q

AI-assisted analysis of golang/go@b6b368adc5 (2026-08-12). Data as JSON: /api/errors/f9ea2b9ef9e1ca3a. Report an issue: GitHub.