LykosAI/StabilityMatrix · error · ValidationException

Input Image is required

Error message

Input Image is required

What it means

Thrown in SelectImageCardViewModel.ApplyStep when a mask-enabled image-to-image workflow is being built but no source image has been loaded (ImageSource is null). The builder cannot construct the LoadImage/mask node graph without a primary input image, so the validation fails early with a clear message.

Solutions

1. Load an input image into the Select Image card before starting the generation
2. Re-open the image if a previous load failed (check the image file still exists at its path)
3. Disable the mask editor if the workflow is meant to be text-to-image, which does not require an input image

Example fix

// before
await vm.ApplyStep(args); // ImageSource == null -> throws
// after
if (vm.ImageSource is null) { await vm.PromptSelectImageAsync(); }
await vm.ApplyStep(args);

if (vm.ImageSource is null)
    throw new ValidationException("Load an input image before generating (mask mode)");

bool hasInputImage = vm.ImageSource is not null;

try { vm.ApplyStep(args); }
catch (ValidationException ex) when (ex.Message == "Input Image is required") { /* show image picker */ }

When it happens

Trigger: ApplyStep with IsMaskEditorEnabled && MaskEditorViewModel.IsMaskEnabled true, and ImageSource == null at the point SetupImagePrimarySourceWithMask is called.

Common situations: User enables the mask editor and paints a mask but never loads a base image; image failed to load from drag-and-drop; the selected image was cleared by a preset reload before ApplyStep ran.

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

• CurrentBitmapSize is null
• API key is required
• Archive must be a zipped tar.
• Definition: ' ' has options, it must have exactly 1 option…
• Definition ' ' has InitialValue of ' ', but it was not…

AI-assisted analysis of LykosAI/StabilityMatrix@af93d6ef57 (2026-09-12). Data as JSON: /api/errors/f9e00dc6991a518e. Report an issue: GitHub.

Appendix: source

Thrown at StabilityMatrix.Avalonia/ViewModels/Inference/SelectImageCardViewModel.cs:161

        if (!SyncBitmapSizeToTabContext)
        {
            return;
        }

        tabContext.SourceImageWidth = CurrentBitmapSize.Width > 0 ? CurrentBitmapSize.Width : 0;
        tabContext.SourceImageHeight = CurrentBitmapSize.Height > 0 ? CurrentBitmapSize.Height : 0;
    }

    /// <inheritdoc />
    public void ApplyStep(ModuleApplyStepEventArgs e)
    {
        // With Mask image
        if (IsMaskEditorEnabled && MaskEditorViewModel.IsMaskEnabled)
        {
            MaskEditorViewModel.PaintCanvasViewModel.CanvasSize = CurrentBitmapSize;

            e.Builder.SetupImagePrimarySourceWithMask(
                ImageSource ?? throw new ValidationException("Input Image is required"),
                !CurrentBitmapSize.IsEmpty
                    ? CurrentBitmapSize
                    : throw new ValidationException("CurrentBitmapSize is null"),
                MaskEditorViewModel.GetCachedOrNewMaskRenderInverseAlphaImage(),
                MaskEditorViewModel.PaintCanvasViewModel.CanvasSize,
                e.Builder.Connections.BatchIndex
            );
        }
        // Normal image only
        else
        {
            e.Builder.SetupImagePrimarySource(
                ImageSource ?? throw new ValidationException("Input Image is required"),
                !CurrentBitmapSize.IsEmpty
                    ? CurrentBitmapSize
                    : throw new ValidationException("CurrentBitmapSize is null"),
                e.Builder.Connections.BatchIndex
            );

View on GitHub (pinned to af93d6ef57)