Seldaek/monolog · error · RuntimeException

Failed to run preg_replace_callback: ${code} / ${message}

Error message

Failed to run preg_replace_callback: ${code} / ${message}

What it means

Error "Failed to run preg_replace_callback: ${code} / ${message}" thrown in Seldaek/monolog.

Source

Thrown at src/Monolog/Handler/BrowserConsoleHandler.php:246

        $style = preg_replace_callback('/macro\s*:(.*?)(?:;|$)/', function (array $m) use ($string, &$colors, &$labels) {
            if (trim($m[1]) === 'autolabel') {
                // Format the string as a label with consistent auto assigned background color
                if (!isset($labels[$string])) {
                    $labels[$string] = $colors[\count($labels) % \count($colors)];
                }
                $color = $labels[$string];

                return "background-color: $color; color: white; border-radius: 3px; padding: 0 2px 0 2px";
            }

            return $m[1];
        }, $style);

        if (null === $style) {
            $pcreErrorCode = preg_last_error();

            throw new \RuntimeException('Failed to run preg_replace_callback: ' . $pcreErrorCode . ' / ' . preg_last_error_msg());
        }

        return $style;
    }

    /**
     * @param  mixed[] $dict
     * @return mixed[]
     */
    private static function dump(string $title, array $dict): array
    {
        $script = [];
        $dict = array_filter($dict, fn ($value) => $value !== null);
        if (\count($dict) === 0) {
            return $script;
        }
        $script[] = self::call('log', self::quote('%c%s'), self::quote('font-weight: bold'), self::quote($title));
        foreach ($dict as $key => $value) {

View on GitHub (pinned to 57eb102834)

When it happens

Trigger: Thrown at src/Monolog/Handler/BrowserConsoleHandler.php:246 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/1e9ae1ae8bfed5eb. Report an issue: GitHub.