slimphp/Slim · error · RuntimeException

Request body media type parser return value must be an array

Error message

Request body media type parser return value must be an array, an object, or null

What it means

Error "Request body media type parser return value must be an array, an object, or null" thrown in slimphp/Slim.

Source

Thrown at Slim/Middleware/BodyParsingMiddleware.php:163

        if ($mediaType === null) {
            return null;
        }

        // Check if this specific media type has a parser registered first
        if (!isset($this->bodyParsers[$mediaType])) {
            // If not, look for a media type with a structured syntax suffix (RFC 6839)
            $parts = explode('+', $mediaType);
            if (count($parts) >= 2) {
                $mediaType = 'application/' . $parts[count($parts) - 1];
            }
        }

        if (isset($this->bodyParsers[$mediaType])) {
            $body = (string)$request->getBody();
            $parsed = $this->bodyParsers[$mediaType]($body);

            if ($parsed !== null && !is_object($parsed) && !is_array($parsed)) {
                throw new RuntimeException(
                    'Request body media type parser return value must be an array, an object, or null'
                );
            }

            return $parsed;
        }

        return null;
    }

    /**
     * @return string|null The serverRequest media type, minus content-type params
     */
    protected function getMediaType(ServerRequestInterface $request): ?string
    {
        $contentType = $request->getHeader('Content-Type')[0] ?? null;

        if (is_string($contentType) && trim($contentType) !== '') {

View on GitHub (pinned to 80900fb39c)

When it happens

Trigger: Thrown at Slim/Middleware/BodyParsingMiddleware.php:163 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of slimphp/Slim@80900fb39c (2026-08-21). Data as JSON: /api/errors/688580eabe7bd6ad. Report an issue: GitHub.