Radarr/Radarr · error · DownloadClientException

Failed to connect to qBittorrent, please check your settings

Error message

Failed to connect to qBittorrent, please check your settings.

What it means

Thrown by QBittorrentProxyV1.ProcessRequest when a WebException (network/transport error) occurs during a generic v1 API request. The message reads 'please check your settings', an inconsistency with the sibling HttpException branch on line 319 which omits 'please'. It is a DownloadClientException (not the Unavailable variant), even though it is network-origin.

Source

Thrown at src/NzbDrone.Core/Download/Clients/QBittorrent/QBittorrentProxyV1.cs:323

                if (response.StatusCode == HttpStatusCode.Forbidden)
                {
                    _logger.Debug("Authentication required, logging in.");

                    AuthenticateClient(requestBuilder, settings, true);

                    request = requestBuilder.Build();

                    response = _httpClient.Execute(request);
                }
            }
            catch (HttpException ex)
            {
                throw new DownloadClientException("Failed to connect to qBittorrent, check your settings.", ex);
            }
            catch (WebException ex)
            {
                throw new DownloadClientException("Failed to connect to qBittorrent, please check your settings.", ex);
            }

            return response.Content;
        }

        private void AuthenticateClient(HttpRequestBuilder requestBuilder, QBittorrentSettings settings, bool reauthenticate = false)
        {
            if (settings.Username.IsNullOrWhiteSpace() || settings.Password.IsNullOrWhiteSpace())
            {
                return;
            }

            var authKey = string.Format("{0}:{1}", requestBuilder.BaseUrl, settings.Password);

            var cookies = _authCookieCache.Find(authKey);

            if (cookies == null || reauthenticate)
            {

View on GitHub (pinned to ca451608dc)

Solutions

Confirm qBittorrent is still running and reachable.
Check for transient network conditions and retry the operation.
Verify Host/Port settings are stable and correct.
Restart qBittorrent if it has become unresponsive.

Defensive patterns

Strategy: try-catch

Validate before calling

// Pre-check reachability to reduce opaque WebExceptions during command execution:
using (var tcp = new System.Net.Sockets.TcpClient())
{
    try { tcp.Connect(settings.Host, settings.Port); }
    catch { /* not reachable */ }
}

Try / catch

try
{
    var content = proxy.ProcessRequest(request, settings);
}
catch (DownloadClientException ex)
{
    logger.Warn(ex, "qBittorrent v1 request failed at the network layer.");
}

Prevention

Confirm qBittorrent is running for the duration of the request.
Treat repeated network errors as a sign qBittorrent restarted.
Re-test the connection after network changes.

When it happens

Trigger: In ProcessRequest, _httpClient.Execute(request) throws a WebException (connection reset, timeout, DNS failure) during a non-auth v1 API call.

Common situations: qBittorrent restarted mid-request; transient network drop; DNS hiccup; connection pool exhaustion; qBittorrent crashed between auth and the request.

Related errors

AI-assisted analysis of Radarr/Radarr@ca451608dc (2026-08-13). Data as JSON: /api/errors/50dc7431235a7aca. Report an issue: GitHub.