LykosAI/StabilityMatrix · error · ArgumentException

No BboxModel

Error message

No BboxModel

What it means

FaceDetailerModule.OnApplyStep throws this ArgumentException when building the UltralyticsDetectorProvider node: GetModelName(faceDetailerCard.BboxModel) returned null, meaning no bbox/face-detection model (e.g. a face_yolov8 or GroundingDINO ultralytics detector) is selected. Unlike the ValidationException siblings, this uses ArgumentException but signals the same missing-selection condition.

Solutions

1. Select a bbox detection model (e.g. bbox/face_yolov8m.pt) in the FaceDetailer card before generating.
2. Download the required ultralytics detector model into the ComfyUI models/ultralytics directory so it appears in the selector.
3. Programmatically set faceDetailerCard.BboxModel to a valid installed model file.
4. Also verify SamModel/SegmModel selections, which the same module validates similarly.

Example fix

// before
faceDetailerCard.IsEnabled = true; // BboxModel null
await vm.Generate(); // ArgumentException
// after
faceDetailerCard.IsEnabled = true;
faceDetailerCard.BboxModel = bboxDetectorFile; // installed ultralytics model
await vm.Generate();

if (faceDetailerCard.BboxModel is null)
    throw new InvalidOperationException("FaceDetailer requires a bbox detection model");

var hasBbox = faceDetailerCard.BboxModel is not null && !string.IsNullOrEmpty(faceDetailerCard.BboxModel.RelativePath);

try { await vm.Generate(); }
catch (ArgumentException ex) when (ex.Message == "No BboxModel")
{
    // prompt user to select/install an ultralytics bbox detector
}

When it happens

Trigger: Including a FaceDetailer module whose card's BboxModel field is unset (or points to a model the resolver cannot name) when ApplyStep builds the workflow.

Common situations: User enables FaceDetailer but leaves the bbox detector dropdown empty; ultralytics/seg detector models (bbox/segm/sam) were never downloaded into ComfyUI's models/ultralytics folder; the previously selected detector file was removed so the selection is stale/null.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• No SelectedModel
• Upscaler is required
• Length cannot be null when latentType is Hunyuan
• Prompt extensions not installed
• No ImageSource

AI-assisted analysis of LykosAI/StabilityMatrix@af93d6ef57 (2026-09-12). Data as JSON: /api/errors/ac5f808efdbeab95. Report an issue: GitHub.

Appendix: source

Thrown at StabilityMatrix.Avalonia/ViewModels/Inference/Modules/FaceDetailerModule.cs:61

            vm.IncludeCategories = ["Settings"];
        });

        await gridVm.GetDialog().ShowAsync();
    }

    protected override void OnApplyStep(ModuleApplyStepEventArgs e)
    {
        var faceDetailerCard = GetCard<FaceDetailerViewModel>();
        if (faceDetailerCard is { InheritSeed: false, SeedCardViewModel.IsRandomizeEnabled: true })
        {
            faceDetailerCard.SeedCardViewModel.GenerateNewSeed();
        }

        var bboxLoader = new ComfyNodeBuilder.UltralyticsDetectorProvider
        {
            Name = e.Builder.Nodes.GetUniqueName(nameof(ComfyNodeBuilder.UltralyticsDetectorProvider)),
            ModelName =
                GetModelName(faceDetailerCard.BboxModel) ?? throw new ArgumentException("No BboxModel"),
        };

        var samplerName =
            (
                faceDetailerCard.IsSamplerSelectionEnabled
                    ? faceDetailerCard.Sampler?.Name
                    : e.Builder.Connections.PrimarySampler?.Name
            ) ?? throw new ArgumentException("No PrimarySampler");

        var schedulerName =
            (
                faceDetailerCard.IsSchedulerSelectionEnabled
                    ? faceDetailerCard.Scheduler?.Name
                    : e.Builder.Connections.PrimaryScheduler?.Name
            ) ?? throw new ArgumentException("No PrimaryScheduler");

        if (schedulerName == "align_your_steps")
        {

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