Seldaek/monolog · error · RuntimeException

Failed to preg_replace_callback: {} / {}

Error message

Failed to preg_replace_callback: {} / {}

What it means

Error "Failed to preg_replace_callback: {} / {}" thrown in Seldaek/monolog.

Source

Thrown at src/Monolog/Utils.php:193

     *
     * @param mixed $data Input to check and convert if needed, passed by ref
     */
    private static function detectAndCleanUtf8(&$data): void
    {
        if (\is_string($data) && preg_match('//u', $data) !== 1) {
            $data = preg_replace_callback(
                '/[\x80-\xFF]+/',
                function (array $m): string {
                    return \function_exists('mb_convert_encoding')
                        ? mb_convert_encoding($m[0], 'UTF-8', 'ISO-8859-1')
                        : (\function_exists('utf8_encode') ? utf8_encode($m[0]) : '');
                },
                $data
            );
            if (!\is_string($data)) {
                $pcreErrorCode = preg_last_error();

                throw new \RuntimeException('Failed to preg_replace_callback: ' . $pcreErrorCode . ' / ' . preg_last_error_msg());
            }
            $data = str_replace(
                ['¤', '¦', '¨', '´', '¸', '¼', '½', '¾'],
                ['€', 'Š', 'š', 'Ž', 'ž', 'Œ', 'œ', 'Ÿ'],
                $data
            );
        }
    }

    /**
     * Converts a string with a valid 'memory_limit' format, to bytes.
     *
     * @param  string|false $val
     * @return int|false    Returns an integer representing bytes. Returns FALSE in case of error.
     */
    public static function expandIniShorthandBytes($val)
    {
        if (!\is_string($val)) {

View on GitHub (pinned to 57eb102834)

When it happens

Trigger: Thrown at src/Monolog/Utils.php:193 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of Seldaek/monolog@57eb102834 (2026-08-17). Data as JSON: /api/errors/b61915c66d8e5bfd. Report an issue: GitHub.