derailed/k9s · error

expected ReferenceRes, but got %T

Error message

expected ReferenceRes, but got %T

What it means

Reference.Render draws the reference browser (NAMESPACE/NAME/GVR rows) and requires a render.ReferenceRes value — the lightweight struct {Namespace, Name, GVR} built when resolving object references. The comma-ok assertion matches the value type, so a *ReferenceRes pointer or any other payload fails with this error, printing the actual %T.

Source

Thrown at internal/render/reference.go:42

		return tcell.ColorCadetBlue
	}
}

// Header returns a header row.
func (Reference) Header(string) model1.Header {
	return model1.Header{
		model1.HeaderColumn{Name: "NAMESPACE"},
		model1.HeaderColumn{Name: "NAME"},
		model1.HeaderColumn{Name: "GVR"},
	}
}

// Render renders a K8s resource to screen.
// BOZO!! Pass in a row with pre-alloc fields??
func (Reference) Render(o any, _ string, r *model1.Row) error {
	ref, ok := o.(ReferenceRes)
	if !ok {
		return fmt.Errorf("expected ReferenceRes, but got %T", o)
	}

	r.ID = client.FQN(ref.Namespace, ref.Name)
	r.Fields = append(r.Fields,
		ref.Namespace,
		ref.Name,
		ref.GVR,
	)

	return nil
}

// ----------------------------------------------------------------------------
// Helpers...

// ReferenceRes represents a reference resource.
type ReferenceRes struct {
	Namespace string

View on GitHub (pinned to 2d3ccc6ba2)

Solutions

1. Pass render.ReferenceRes by value
2. Bind the Reference renderer only to views that produce ReferenceRes rows
3. Use the comma-ok form in wrappers and skip mismatches
4. Check the %T in the error to find the offending producer

Example fix

// before
err := refRenderer.Render(&render.ReferenceRes{Namespace: ns, Name: n, GVR: gvr}, ns, row)
// after
err := refRenderer.Render(render.ReferenceRes{Namespace: ns, Name: n, GVR: gvr}, ns, row)

// gate before invoking the reference renderer
if _, ok := o.(render.ReferenceRes); !ok {
	return fmt.Errorf("reference view requires render.ReferenceRes value, got %T", o)
}
err := refRenderer.Render(o, ns, row)

func isReferenceRes(o any) bool {
	_, ok := o.(render.ReferenceRes)
	return ok
}

if err := refRenderer.Render(o, ns, row); err != nil {
	slog.Warn("reference row skipped", "type", fmt.Sprintf("%T", o), slogs.Error, err)
	return nil // drop the row, keep the view alive
}

When it happens

Trigger: Calling Reference{}.Render with &ReferenceRes{...} (pointer), an unstructured resource, or a typed object; wiring the reference renderer to views that emit different row types.

Common situations: Building describe-style or cross-reference views; plugins that resolve GVK/GVR references; refactors that change the reference walker's output to pointers.

Related errors

• expecting a ForwardRes but got %T
• expected Unstructured, but got %T
• expected Unstructured, but got %T
• expecting PolicyRes but got %T
• expected Unstructured, but got %T

AI-assisted analysis of derailed/k9s@2d3ccc6ba2 (2026-08-15). Data as JSON: /api/errors/ab1b2579c8491baf. Report an issue: GitHub.