symfony/http-kernel · error · InvalidArgumentException

The log level " " does not exist.

Error message

The log level "%s" does not exist.

What it means

Symfony's monolog-free Log\Logger constructor validates that the given minimum level is a known PSR-3 level; if the string is not in its LEVELS map, it throws InvalidArgumentException immediately at construction time. This is fail-fast validation of a configuration value.

Solutions

1. Use a valid PSR-3 LogLevel constant (e.g. LogLevel::WARNING)
2. Fix typos such as 'warn' -> 'warning' and lowercase the value (strtolower)
3. Sanitize env-derived levels before passing them to the constructor
4. Catch InvalidArgumentException at boot to surface bad config early

Example fix

// before
new Logger('warn', $output);

// after
use Psr\Log\LogLevel;
new Logger(LogLevel::WARNING, $output);

$valid = ['debug','info','notice','warning','error','critical','alert','emergency'];
if (!in_array(strtolower($minLevel), $valid, true)) {
    throw new \InvalidArgumentException("Invalid log level: $minLevel");
}

try { $logger = new \Symfony\Component\HttpKernel\Log\Logger($minLevel, $output); } catch (\InvalidArgumentException $e) { /* fall back to default level */ $logger = new \Symfony\Component\HttpKernel\Log\Logger('error', $output); }

When it happens

Trigger: Constructing Symfony\Component\HttpKernel\Log\Logger (or a service wired to it) with a $minLevel string that is not one of debug/info/notice/warning/error/critical/alert/emergency (or a valid verbosity constant mapping).

Common situations: Typo in a YAML/services log level config (e.g. 'warn' instead of 'warning'); uppercase levels like 'ERROR'; env var LOG_LEVEL containing an invalid value; custom factory passing verbosity strings directly.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

• Invalid log level " ".
• Unable to open " ".
• The "$tokens" argument of
• Message built by getControllerError(): e.g. Function
• Invalid dump format: " ".

AI-assisted analysis of symfony/http-kernel@aa3a39d728 (2026-09-13). Data as JSON: /api/errors/69dd5822b96fec55. Report an issue: GitHub.

Appendix: source

Thrown at Log/Logger.php:71

    /** @var resource|null */
    private $handle;

    /**
     * @param string|resource|null $output
     */
    public function __construct(?string $minLevel = null, $output = null, ?callable $formatter = null, private readonly ?RequestStack $requestStack = null, bool $debug = false)
    {
        $minLevel ??= match ((int) ($_ENV['SHELL_VERBOSITY'] ?? $_SERVER['SHELL_VERBOSITY'] ?? 0)) {
            -1 => LogLevel::ERROR,
            1 => LogLevel::NOTICE,
            2 => LogLevel::INFO,
            3 => LogLevel::DEBUG,
            default => null === $output || 'php://stdout' === $output || 'php://stderr' === $output ? LogLevel::ERROR : LogLevel::WARNING,
        };

        if (!isset(self::LEVELS[$minLevel])) {
            throw new InvalidArgumentException(\sprintf('The log level "%s" does not exist.', $minLevel));
        }

        $this->minLevelIndex = self::LEVELS[$minLevel];
        $this->formatter = null !== $formatter ? $formatter(...) : $this->format(...);
        if ($output && false === $this->handle = \is_string($output) ? @fopen($output, 'a') : $output) {
            throw new InvalidArgumentException(\sprintf('Unable to open "%s".', $output));
        }
        $this->debug = $debug;
    }

    public function enableDebug(): void
    {
        $this->debug = true;
    }

    public function log($level, $message, array $context = []): void
    {
        if (!isset(self::LEVELS[$level])) {

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