kovidgoyal/kitty · error

%s is not a valid value for signature: %#v with error: %w

Error message

%s is not a valid value for signature: %#v with error: %w

What it means

A type signature was supplied and parsed successfully, but the value string still cannot be parsed as that type by dbus.ParseVariant. The offending value and signature are both included.

Source

Thrown at kittens/desktop_ui/portal.go:245

}

func ParseValueWithSignature(value, value_type_signature string) (v dbus.Variant, err error) {
	var s dbus.Signature
	if value_type_signature != "" {
		if value_type_signature[0] == '@' {
			value_type_signature = value_type_signature[1:]
		}
		s, err = dbus.ParseSignature(value_type_signature)
		if err != nil {
			return dbus.Variant{}, fmt.Errorf("%s is not a valid type signature: %w", value_type_signature, err)
		}
	}
	v, err = dbus.ParseVariant(value, s)
	if err != nil {
		if value_type_signature == "" {
			return dbus.Variant{}, fmt.Errorf("could not guess the data type of: %s with error: %w", value, err)
		}
		return dbus.Variant{}, fmt.Errorf("%s is not a valid value for signature: %#v with error: %w", value, value_type_signature, err)
	}
	return v, nil
}

func ParseValue(value string) (dbus.Variant, error) {
	return ParseValueWithSignature(value, "")
}

type ShowSettingsOptions struct {
	AsJson             bool
	AllowOtherBackends bool
	InNamespace        []string
}

func fetch_settings(conn *dbus.Conn, namespaces ...string) (ans ReadAllType, err error) {
	path := "/" + strings.ToLower(strings.ReplaceAll(DESKTOP_PORTAL_NAME, ".", "/"))
	obj := conn.Object(DESKTOP_PORTAL_NAME, dbus.ObjectPath(path))
	interface_name := strings.ReplaceAll(DESKTOP_PORTAL_NAME, "Desktop", "Settings")

View on GitHub (pinned to 6d5d0c4406)

Solutions

1. Match the value to the signature: use 'true'/'false' for @b, digits for @u/@i/@x, quoted text for @s
2. Read the setting's expected type from the portal settings docs or show-settings output
3. Use the exact GVariant text format documented at docs.gtk.org/glib/gvariant-text-format.html

Example fix

# before
kitten desktop-ui set ns key --value-type '@u' hello
# after
kitten desktop-ui set ns key --value-type '@s' 'hello'

if _, err := dbus.ParseVariant(value, mustSignature(sig)); err != nil {
    return fmt.Errorf("value %q does not match signature %q", value, sig)
}

v, err := portal.ParseValueWithSignature(value, sig)
if err != nil {
    // fall back to guessing, or surface signature mismatch to the user
}

When it happens

Trigger: Passing 'hello' with signature '@u', or '1,2' with signature '@i', etc. — any value/signature mismatch.

Common situations: Wrong signature guessed for a setting; values from other tools that use different scalar syntax; boolean passed as 'yes'/'1' instead of 'true'/'false'.

Related errors

• %s is not a valid type signature: %w
• could not guess the data type of: %s with error: %w
• failed to export interface: %s at object path: %s with error
• failed to export properties with error: %w
• failed to export introspected methods with error: %w

AI-assisted analysis of kovidgoyal/kitty@6d5d0c4406 (2026-08-27). Data as JSON: /api/errors/3bee89d8b597581c. Report an issue: GitHub.