Radarr/Radarr · error · DownloadClientException

Failed to add nzb {0}

Error message

Failed to add nzb {0}

What it means

Thrown by NzbVortex.AddFromNzbFile when _proxy.DownloadNzb() returns null instead of a response ID string. The proxy's DownloadNzb sends the NZB file to NZBVortex's nzb/add endpoint and returns response.Id. A null return means NZBVortex did not provide a download ID despite accepting the request, which Radarr treats as a failure to add.

Source

Thrown at src/NzbDrone.Core/Download/Clients/NzbVortex/NzbVortex.cs:43

                       IDiskProvider diskProvider,
                       IRemotePathMappingService remotePathMappingService,
                       IValidateNzbs nzbValidationService,
                       Logger logger,
                       ILocalizationService localizationService)
            : base(httpClient, configService, diskProvider, remotePathMappingService, nzbValidationService, logger, localizationService)
        {
            _proxy = proxy;
        }

        protected override string AddFromNzbFile(RemoteMovie remoteMovie, string filename, byte[] fileContents)
        {
            var priority = remoteMovie.Movie.MovieMetadata.Value.IsRecentMovie ? Settings.RecentMoviePriority : Settings.OlderMoviePriority;

            var response = _proxy.DownloadNzb(fileContents, filename, priority, Settings);

            if (response == null)
            {
                throw new DownloadClientException("Failed to add nzb {0}", filename);
            }

            return response;
        }

        public override string Name => "NZBVortex";

        public override IEnumerable<DownloadClientItem> GetItems()
        {
            List<NzbVortexQueueItem> vortexQueue;

            try
            {
                vortexQueue = _proxy.GetQueue(30, Settings);
            }
            catch (DownloadClientException ex)
            {
                _logger.Warn("Couldn't get download queue. {0}", ex.Message);

View on GitHub (pinned to ca451608dc)

Solutions

1. Verify the NZB file is valid and not corrupted before it reaches the download client.
2. Check that the NZBVortex group/category (TvCategory) in Radarr settings exists in NZBVortex.
3. Review NZBVortex logs for errors at the time of the add attempt.
4. Upgrade NZBVortex to a version compatible with the API level Radarr expects.
5. Test adding the same NZB manually through the NZBVortex UI to isolate the issue.

Example fix

// before
var response = _proxy.DownloadNzb(fileContents, filename, priority, Settings);
if (response == null)
{
    throw new DownloadClientException("Failed to add nzb {0}", filename);
}

// after — log the NZBVortex response for diagnosis before throwing
var response = _proxy.DownloadNzb(fileContents, filename, priority, Settings);
if (response == null)
{
    _logger.Error("NZBVortex returned null ID for NZB: {0}", filename);
    throw new DownloadClientException("Failed to add nzb {0}", filename);
}

// Validate NZB content before sending to NZBVortex
if (fileContents == null || fileContents.Length == 0)
{
    throw new ArgumentException("NZB file contents are empty");
}
// Verify the category exists in NZBVortex
var groups = _proxy.GetGroups(settings);
if (settings.TvCategory.IsNotNullOrWhiteSpace() && !groups.Any(g => g.Name == settings.TvCategory))
{
    return $"NZBVortex group '{settings.TvCategory}' does not exist";
}

static bool IsNzbVortexAddFailed(Exception ex) => ex is DownloadClientException dce && dce.Message.Contains("Failed to add nzb");

try
{
    var downloadId = _proxy.DownloadNzb(fileContents, filename, priority, Settings);
}
catch (DownloadClientException ex) when (ex.Message.Contains("Failed to add nzb"))
{
    _logger.Error(ex, "NZBVortex did not return a download ID. Check NZBVortex logs.");
    // The release was not added — do not mark as downloaded
}
catch (DownloadClientException ex)
{
    _logger.Error(ex, "NZBVortex error.");
}

When it happens

Trigger: _proxy.DownloadNzb(fileContents, filename, priority, Settings) returns null. This occurs when the NzbVortexAddResponse from the nzb/add endpoint has a null or empty Id field.

Common situations: NZBVortex encountered an internal error processing the NZB but did not return an explicit error, the NZB file was malformed or empty, the group/category setting points to a non-existent NZBVortex group, or a version mismatch causes the response to lack the expected Id field.

Related errors

• Unable to connect to NZBVortex, please check your settings
• Authentication failed, check your API Key
• NZBGet rejected the NZB for an unknown reason
• Failed to add NZB task to Download Station
• Not logged

AI-assisted analysis of Radarr/Radarr@ca451608dc (2026-08-13). Data as JSON: /api/errors/229776ad4170c93d. Report an issue: GitHub.