What causes "Invalid response from the server." in octobercms/october?

Capture the raw response (curl the same endpoint) and inspect what is actually returned instead of JSON

octobercms/october · error · ApplicationException

system::lang.server.response_invalid

system::lang.server.response_invalid

Error message

Invalid response from the server.

What it means

After a 200 response, requestServerData() decodes the gateway body with @json_decode; the catch around it throws 'Invalid response from the server' (system::lang.server.response_invalid) if decoding raises. This indicates the update server returned something that is not valid JSON — an HTML error page, a serialized blob, or a truncated body. It is the 'server answered but spoke the wrong protocol' branch of the updater's response validation.

Source

Thrown at modules/system/classes/updatemanager/HasGatewayAccess.php:62

        if ($result->status() === 404) {
            throw new ApplicationException(Lang::get('system::lang.server.response_not_found'));
        }

        if ($result->status() !== 200) {
            throw new ApplicationException(
                strlen($contents)
                ? $contents
                : Lang::get('system::lang.server.response_empty')
            );
        }

        $resultData = false;

        try {
            $resultData = @json_decode($contents, true);
        }
        catch (Exception $ex) {
            throw new ApplicationException(Lang::get('system::lang.server.response_invalid'));
        }

        if ($resultData === false || (is_string($resultData) && !strlen($resultData))) {
            throw new ApplicationException(Lang::get('system::lang.server.response_invalid'));
        }

        return $resultData;
    }

    /**
     * requestServerFile downloads a file from the update server.
     * @param string $uri
     * @param string $fileCode
     * @param array $postData
     */
    public function requestServerFile($uri, $fileCode, $postData = [])
    {
        $filePath = $this->getFilePath($fileCode);

View on GitHub (pinned to b608633a7e)

Solutions

Capture the raw response (curl the same endpoint) and inspect what is actually returned instead of JSON
If a captive portal or proxy injects HTML, fix the network path or proxy exclusions for the gateway host
For custom gateways, ensure every endpoint the updater hits emits application/json only
Verify the body isn't truncated by TLS inspection or output compression middleware

Defensive patterns

Strategy: try-catch

Try / catch

try {
    $response = \System\Classes\UpdateManager::instance()->requestServerData($uri, $postData);
} catch (\October\Rain\Exception\ApplicationException $ex) {
    if (str_contains($ex->getMessage(), 'Invalid response')) {
        // gateway spoke non-JSON (captive portal/proxy) — log the context, don't retry blindly
        Log::warning('Update gateway returned non-JSON payload', ['uri' => $uri]);
    }
    throw $ex;
}

Prevention

Verify server egress reaches the gateway cleanly (no captive portals/WAF interstitials)
For custom gateways, assert Content-Type: application/json on every updater route in tests
Keep a curl-based health check for gateway endpoints in your monitoring

When it happens

Trigger: Gateway returns 200 with HTML (captive portal, login page, proxy interstitial), partially downloaded body, or BOM/prefix noise before the JSON; any update/marketplace request going through requestServerData().

Common situations: Captive Wi-Fi / hotel portal intercepting HTTPS; a custom update server returning rendered pages on some routes; response compression or charset issues corrupting the body; ISP-level content rewriting.

Related errors

AI-assisted analysis of octobercms/october@b608633a7e (2026-08-21). Data as JSON: /api/errors/103b6532f9c4b03f. Report an issue: GitHub.