Seldaek/monolog · error · RuntimeException

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

Error message

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

What it means

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

Source

Thrown at src/Monolog/Formatter/LineFormatter.php:178

            if (\count($vars['extra']) === 0) {
                unset($vars['extra']);
                $output = str_replace('%extra%', '', $output);
            }
        }

        foreach ($vars as $var => $val) {
            if (false !== strpos($output, '%'.$var.'%')) {
                $output = str_replace('%'.$var.'%', $this->stringify($val), $output);
            }
        }

        // remove leftover %extra.xxx% and %context.xxx% if any
        if (false !== strpos($output, '%')) {
            $output = preg_replace('/%(?:extra|context)\..+?%/', '', $output);
            if (null === $output) {
                $pcreErrorCode = preg_last_error();

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

        return $output;
    }

    public function formatBatch(array $records): string
    {
        $message = '';
        foreach ($records as $record) {
            $message .= $this->format($record);
        }

        return $message;
    }

    /**
     * @param mixed $value

View on GitHub (pinned to 57eb102834)

When it happens

Trigger: Thrown at src/Monolog/Formatter/LineFormatter.php:178 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/211d4adb8cb4e1ca. Report an issue: GitHub.