PHPOffice/PhpSpreadsheet · error · PhpOffice\PhpSpreadsheet\Reader\Exception

Double encoding not permitted

Error message

Double encoding not permitted

What it means

Error "Double encoding not permitted" thrown in PHPOffice/PhpSpreadsheet.

Source

Thrown at src/PhpSpreadsheet/Reader/Security/XmlScanner.php:48

    {
        $this->callback = $callback;
    }

    private static function forceString(mixed $arg): string
    {
        return is_string($arg) ? $arg : '';
    }

    private function toUtf8(string $xml): string
    {
        $charset = $this->findCharSet($xml);
        $foundUtf7 = $charset === 'UTF-7';
        if ($charset !== 'UTF-8') {
            $testStart = '/^.{0,4}\s*<?xml/s';
            $startWithXml1 = preg_match($testStart, $xml);
            $xml = self::forceString(mb_convert_encoding($xml, 'UTF-8', $charset));
            if ($startWithXml1 === 1 && preg_match($testStart, $xml) !== 1) {
                throw new Reader\Exception('Double encoding not permitted');
            }
            $foundUtf7 = $foundUtf7 || (preg_match(self::ENCODING_UTF7, $xml) === 1);
            $xml = preg_replace(self::ENCODING_PATTERN, '', $xml) ?? $xml;
        } else {
            $foundUtf7 = $foundUtf7 || (preg_match(self::ENCODING_UTF7, $xml) === 1);
        }
        if ($foundUtf7) {
            throw new Reader\Exception('UTF-7 encoding not permitted');
        }
        if (substr($xml, 0, Reader\Csv::UTF8_BOM_LEN) === Reader\Csv::UTF8_BOM) {
            $xml = substr($xml, Reader\Csv::UTF8_BOM_LEN);
        }

        return $xml;
    }

    private function findCharSet(string $xml): string
    {

View on GitHub (pinned to 65b080eef4)

When it happens

Trigger: Thrown at src/PhpSpreadsheet/Reader/Security/XmlScanner.php:48 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of PHPOffice/PhpSpreadsheet@65b080eef4 (2026-08-17). Data as JSON: /api/errors/c4f306742c9c7bf0. Report an issue: GitHub.