Radarr/Radarr · warning · NotSupportedException

{Name} does not support marking items as imported

Error message

{Name} does not support marking items as imported

What it means

The base DownloadClientBase class provides a default MarkItemAsImported implementation that throws NotSupportedException. This is a virtual method meant to be overridden by download clients that support marking a completed item as imported (e.g. to tell the client the file has been moved). Clients that don't implement it (like some older or simpler clients) hit this default and throw.

Source

Thrown at src/NzbDrone.Core/Download/DownloadClientBase.cs:191

                    DetailedDescription = string.Format("The folder you specified does not exist or is inaccessible. Please verify the folder permissions for the user account '{0}', which is used to execute Radarr.", Environment.UserName)
                };
            }

            if (mustBeWritable && !_diskProvider.FolderWritable(folder))
            {
                _logger.Error("Folder '{0}' is not writable.", folder);
                return new NzbDroneValidationFailure(propertyName, "Unable to write to folder")
                {
                    DetailedDescription = string.Format("The folder you specified is not writable. Please verify the folder permissions for the user account '{0}', which is used to execute Radarr.", Environment.UserName)
                };
            }

            return null;
        }

        public virtual void MarkItemAsImported(DownloadClientItem downloadClientItem)
        {
            throw new NotSupportedException(Name + " does not support marking items as imported");
        }
    }
}

View on GitHub (pinned to ca451608dc)

Solutions

1. Switch to a download client that implements MarkItemAsImported (e.g. qBittorrent, Deluge, Transmission, rTorrent)
2. Disable settings that trigger the MarkItemAsImported call (e.g. advanced import completion handling)
3. If developing a custom client, override MarkItemAsImported in your DownloadClientBase subclass

Example fix

// before: base class throws NotSupportedException
public class MyDownloadClient : DownloadClientBase<MySettings>
{
    // no override
}

// after: override to support or no-op
public class MyDownloadClient : DownloadClientBase<MySettings>
{
    public override void MarkItemAsImported(DownloadClientItem downloadClientItem)
    {
        // implement client-specific API call to mark as imported
    }
}

// Check capability before calling
var clientType = downloadClient.GetType();
var method = clientType.GetMethod("MarkItemAsImported", BindingFlags.Instance | BindingFlags.Public);
var isOverridden = method != null && method.DeclaringType != typeof(DownloadClientBase<>);
// Only call if overridden
if (isOverridden)
{
    downloadClient.MarkItemAsImported(item);
}

// Type guard: check if client supports MarkItemAsImported by testing
// whether the method is overridden from the base class
public static bool SupportsMarkItemAsImported(IDownloadClient client)
{
    var method = client.GetType().GetMethod("MarkItemAsImported");
    return method != null && method.DeclaringType != typeof(DownloadClientBase<>) &&
           method.DeclaringType?.BaseType != null;
}

try
{
    downloadClient.MarkItemAsImported(item);
}
catch (NotSupportedException)
{
    _logger.Debug("{0} does not support MarkItemAsImported, skipping.", downloadClient.Name);
    // This is expected for some clients — continue without failing the import
}

When it happens

Trigger: Calling MarkItemAsImported(downloadClientItem) on a download client that does not override the virtual method. This happens when Radarr's import completed-download handling attempts to signal the download client after a successful import, but the specific client implementation (e.g. a basic or blackhole client) doesn't support this feature.

Common situations: Using a download client like Pneumatic or a blackhole client that has no API for marking items as imported; enabling 'Remove Completed' or similar import-related settings that trigger MarkItemAsImported on a client that doesn't support it; upgrading to a Radarr version that newly calls MarkItemAsImported during the import flow.

Related errors

• Failed to fetch list of contents of torrent: {item.DownloadI
• {Name} does not support marking items as imported
• Magnet not supported by download client. ({0})
• CustomFormatUnknownCondition
• CustomFormatUnknownConditionOption

AI-assisted analysis of Radarr/Radarr@ca451608dc (2026-08-13). Data as JSON: /api/errors/4ca0a18d379ed973. Report an issue: GitHub.