What causes "No VAE Selected" in LykosAI/StabilityMatrix?

Select a VAE (e.g. Wan VAE file) in the model card's VAE dropdown before generating.

LykosAI/StabilityMatrix · error · ValidationException

No VAE Selected

Error message

No VAE Selected

What it means

Building the Wan workflow's VAE stage requires a selected VAE file. If SelectedVae is null, SelectedVae?.RelativePath is null and the builder throws 'No VAE Selected' instead of creating a VAELoader with an empty VaeName. It is a pre-flight validation done on the client so ComfyUI never sees an invalid graph.

Solutions

Select a VAE (e.g. Wan VAE file) in the model card's VAE dropdown before generating.
Place the VAE .safetensors in the shared vae folder and refresh the model list if it does not appear.
Re-select and re-save the workflow after files were moved or restored.
If the workflow legitimately needs no external VAE, use a card/workflow variant that does not require a VAE loader selection.

Example fix

// before
VaeName = SelectedVae?.RelativePath ?? throw new ValidationException("No VAE Selected"),
// after
if (SelectedVae is null)
    throw new ValidationException("No VAE Selected");
// then: VaeName = SelectedVae.RelativePath

Defensive patterns

Strategy: validation

Validate before calling

if (card.SelectedVae is null)
    throw new ValidationException("No VAE Selected");

Type guard

bool HasVae(WanModelCardViewModel c) => c.SelectedVae != null && !string.IsNullOrEmpty(c.SelectedVae.RelativePath);

Try / catch

try { card.ApplyStep(e); }
catch (ValidationException ex) when (ex.Message == "No VAE Selected")
{ /* prompt user to choose a VAE */ }

Prevention

Mark VAE dropdown as required unless the workflow variant omits it
Validate file existence after any model-folder reorganization
Include VAE in a single pre-apply validation of all selections
Re-resolve saved VAE paths on workflow load

When it happens

Trigger: Generating a Wan workflow with no VAE selected in the model card's VAE dropdown, hitting WanModelCardViewModel.cs:242.

Common situations: User assumed the checkpoint embeds its VAE and skipped the dropdown; the .safetensors VAE file was deleted or moved out of the shared vae folder; a saved workflow references a VAE path that no longer resolves.

Understand the failure class

Background: "Must pass :limit option" / "Missing required option" — required option errors explained — this error's family across 41 libraries.

Related errors

AI-assisted analysis of LykosAI/StabilityMatrix@af93d6ef57 (2026-09-12). Data as JSON: /api/errors/350864787ab2eb03. Report an issue: GitHub.

Appendix: source

Thrown at StabilityMatrix.Avalonia/ViewModels/Inference/WanModelCardViewModel.cs:242

                .Output
            : e
                .Nodes.AddTypedNode(
                    new ComfyNodeBuilder.CLIPLoader
                    {
                        Name = e.Nodes.GetUniqueName(nameof(ComfyNodeBuilder.CLIPLoader)),
                        ClipName = clipName,
                        Type = "wan",
                    }
                )
                .Output;

        e.Builder.Connections.Base.Clip = clipOutput;

        var vaeLoader = e.Nodes.AddTypedNode(
            new ComfyNodeBuilder.VAELoader
            {
                Name = e.Nodes.GetUniqueName(nameof(ComfyNodeBuilder.VAELoader)),
                VaeName = SelectedVae?.RelativePath ?? throw new ValidationException("No VAE Selected"),
            }
        );
        e.Builder.Connections.Base.VAE = vaeLoader.Output;
        e.Builder.Connections.PrimaryVAE = vaeLoader.Output;

        if (ExtraNetworksStackCardViewModel.Cards.OfType<LoraModule>().Any(x => x.IsEnabled))
        {
            ExtraNetworksStackCardViewModel.ApplyStep(e);
        }

        if (!IsClipVisionEnabled)
            return;

        var clipVisionLoader = e.Nodes.AddTypedNode(
            new ComfyNodeBuilder.CLIPVisionLoader
            {
                Name = e.Nodes.GetUniqueName(nameof(ComfyNodeBuilder.CLIPVisionLoader)),
                ClipName =

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