github/copilot-sdk · error

elicitation schema property

Error message

elicitation schema property %q is nil

What it means

Elicitation schemas are maps of property name to property definition. When converting a Go map-based ElicitationSchema into the rpc schema, a property entry that is nil cannot represent a valid JSON schema property, so the library rejects it with this error naming the property key. It enforces that every schema property carries an actual definition.

Solutions

1. Ensure every entry in the schema Properties map is a non-nil property definition
2. Check for nil values before calling the UI method and skip or fill them
3. Construct properties via typed structs or rpc.UIElicitationSchemaProperty to guarantee non-nil
4. Initialize the property map fully before passing it to Elicitation

Example fix

// before
props := map[string]any{"age": nil}
// after
props := map[string]any{"age": map[string]any{"type": "number"}}

for name, p := range schema.Properties {
    if p == nil {
        return fmt.Errorf("schema property %q is nil", name)
    }
}

func hasNilProperties(props map[string]any) bool {
    for _, p := range props { if p == nil { return true } }
    return false
}

res, err := ui.Elicitation(ctx, msg, schema)
if err != nil && strings.Contains(err.Error(), "schema property") && strings.Contains(err.Error(), "is nil") {
    return fmt.Errorf("fix schema: %w", err)
}

When it happens

Trigger: Passing ElicitationSchema{Properties: map[string]any{"name": nil}} to Elicitation or related UI methods, producing a nil entry for key "name".

Common situations: Building schemas dynamically where a variable holding the property definition was never assigned; copying schema maps and dropping values; JSON round-trips that turned omitted definitions into nil.

Related errors

• marshal elicitation schema property
• marshal elicitation schema wrapper for property
• decode elicitation schema property
• decode elicitation schema property
• sessionFs.initialCwd is required

AI-assisted analysis of github/copilot-sdk@cd8cf15dc3 (2026-09-09). Data as JSON: /api/errors/bc214ccb1f17ce5e. Report an issue: GitHub.

Appendix: source

Thrown at go/session.go:1211

		for name, property := range schema.Properties {
			rpcProperty, err := toRPCUIElicitationSchemaProperty(name, property)
			if err != nil {
				return rpc.UIElicitationSchema{}, err
			}
			properties[name] = rpcProperty
		}
	}

	return rpc.UIElicitationSchema{
		Properties: properties,
		Required:   append([]string(nil), schema.Required...),
		Type:       rpc.UIElicitationSchemaTypeObject,
	}, nil
}

func toRPCUIElicitationSchemaProperty(name string, property any) (rpc.UIElicitationSchemaProperty, error) {
	if property == nil {
		return nil, fmt.Errorf("elicitation schema property %q is nil", name)
	}
	if rpcProperty, ok := property.(rpc.UIElicitationSchemaProperty); ok {
		return rpcProperty, nil
	}

	data, err := json.Marshal(property)
	if err != nil {
		return nil, fmt.Errorf("marshal elicitation schema property %q: %w", name, err)
	}
	wrapperData, err := json.Marshal(struct {
		Properties map[string]json.RawMessage  `json:"properties"`
		Type       rpc.UIElicitationSchemaType `json:"type"`
	}{
		Properties: map[string]json.RawMessage{name: data},
		Type:       rpc.UIElicitationSchemaTypeObject,
	})
	if err != nil {
		return nil, fmt.Errorf("marshal elicitation schema wrapper for property %q: %w", name, err)

View on GitHub (pinned to cd8cf15dc3)