cakephp/cakephp · error · CakeException

Invalid format for MO translations file

Error message

Invalid format for MO translations file

What it means

After opening a .mo file, MoFileParser::parse() stats it and rejects it if fstat fails or the file is smaller than the 28-byte MO magic header (MO_HEADER_SIZE). This means the file exists but is too small/empty to be a valid GNU MO file. CakePHP throws the same message later when the magic number is wrong, so the file may be truncated or not a MO file at all.

Solutions

1. Regenerate the .mo file with msgfmt (or cake i18n extract/compile pipeline) and verify size > 0
2. Confirm the file is actually a compiled .mo (file magic via `file translation.mo`) and not a .po or HTML error page
3. Re-upload/redeploy the translation file; verify integrity with checksum after transfer
4. Add a pre-check: filesize($path) >= 28 before parsing

Example fix

// before
$entries = $parser->parse($path); // truncated .mo
// after
if (filesize($path) < 28) { // MoFileParser::MO_HEADER_SIZE
    throw new RuntimeException("Truncated MO file: $path");
}
$entries = $parser->parse($path);

$size = @filesize($path);
if ($size === false || $size < 28) throw new RuntimeException("Truncated/invalid MO: $path");

try {
    $entries = (new MoFileParser())->parse($path);
} catch (\Cake\Core\Exception\CakeException $e) {
    if ($e->getMessage() === 'Invalid format for MO translations file') {
        $entries = [];
    } else { throw $e; }
}

When it happens

Trigger: Calling parse() on an empty file, a partially written/truncated .mo, a file whose stat fails, or on a non-MO file smaller than MO_HEADER_SIZE.

Common situations: msgfmt run interrupted leaving a 0-byte .mo; git LFS/checkout artifacts; copying a .po where a .mo was expected; disk full during deployment truncating the file.

Understand the failure class

Background: "failed to read file", EACCES, ENOENT and "could not read <path>" errors: when a program can't read a file from disk — this error's family across 49 libraries.

Related errors

• Cannot open resource
• Length must be > 0
• Could not find class
• Cannot open resource
• Cannot read file content of

AI-assisted analysis of cakephp/cakephp@1128eba9b0 (2026-09-12). Data as JSON: /api/errors/aabc1f2bb2551e57. Report an issue: GitHub.

Appendix: source

Thrown at src/I18n/Parser/MoFileParser.php:70

    /**
     * Parses machine object (MO) format, independent of the machine's endian it
     * was created on. Both 32bit and 64bit systems are supported.
     *
     * @param string $file The file to be parsed.
     * @return array List of messages extracted from the file
     * @throws \Cake\Core\Exception\CakeException If stream content has an invalid format.
     */
    public function parse(string $file): array
    {
        $stream = fopen($file, 'rb');
        if ($stream === false) {
            throw new CakeException(sprintf('Cannot open resource `%s`', $file));
        }

        $stat = fstat($stream);

        if ($stat === false || $stat['size'] < self::MO_HEADER_SIZE) {
            throw new CakeException('Invalid format for MO translations file');
        }
        /** @var array $magic */
        $magic = unpack('V1', (string)fread($stream, 4));
        $magic = hexdec(substr(dechex(current($magic)), -8));

        if ($magic === self::MO_LITTLE_ENDIAN_MAGIC) {
            $isBigEndian = false;
        } elseif ($magic === self::MO_BIG_ENDIAN_MAGIC) {
            $isBigEndian = true;
        } else {
            throw new CakeException('Invalid format for MO translations file');
        }

        // offset formatRevision
        fread($stream, 4);

        $count = $this->_readLong($stream, $isBigEndian);
        $offsetId = $this->_readLong($stream, $isBigEndian);

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