Seldaek/monolog · error · InvalidArgumentException

Level "${level}" is not defined, use one of: ${levels}

Error message

Level "${level}" is not defined, use one of: ${levels}

What it means

Error "Level "${level}" is not defined, use one of: ${levels}" thrown in Seldaek/monolog.

Source

Thrown at src/Monolog/Logger.php:490

    /**
     * Converts PSR-3 levels to Monolog ones if necessary
     *
     * @param  int|string|Level|LogLevel::*      $level Level number (monolog) or name (PSR-3)
     * @throws \Psr\Log\InvalidArgumentException If level is not defined
     *
     * @phpstan-param value-of<Level::VALUES>|value-of<Level::NAMES>|Level|LogLevel::* $level
     */
    public static function toMonologLevel(string|int|Level $level): Level
    {
        if ($level instanceof Level) {
            return $level;
        }

        if (\is_string($level)) {
            if (is_numeric($level)) {
                $levelEnum = Level::tryFrom((int) $level);
                if ($levelEnum === null) {
                    throw new InvalidArgumentException('Level "'.$level.'" is not defined, use one of: '.implode(', ', Level::NAMES + Level::VALUES));
                }

                return $levelEnum;
            }

            // Contains first char of all log levels and avoids using strtoupper() which may have
            // strange results depending on locale (for example, "i" will become "İ" in Turkish locale)
            $upper = strtr(substr($level, 0, 1), 'dinweca', 'DINWECA') . strtolower(substr($level, 1));
            if (\defined(Level::class.'::'.$upper)) {
                return \constant(Level::class . '::' . $upper);
            }

            throw new InvalidArgumentException('Level "'.$level.'" is not defined, use one of: '.implode(', ', Level::NAMES + Level::VALUES));
        }

        $levelEnum = Level::tryFrom($level);
        if ($levelEnum === null) {
            throw new InvalidArgumentException('Level "'.var_export($level, true).'" is not defined, use one of: '.implode(', ', Level::NAMES + Level::VALUES));

View on GitHub (pinned to 57eb102834)

When it happens

Trigger: Thrown at src/Monolog/Logger.php:490 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/303b4b0304d19dfb. Report an issue: GitHub.