tailscale/tailscale · error

cannot send files: target is not advertising a file sharing

Error message

cannot send files: target is not advertising a file sharing API

What it means

Error "cannot send files: target is not advertising a file sharing API" thrown in tailscale/tailscale.

Source

Thrown at cmd/tailscale/cli/file.go:509

		return "", isOffline, errors.New("cannot send files: local Tailscale is not connected to the tailnet")

	case ipnstate.TaildropTargetMissingCap:
		return "", isOffline, errors.New("cannot send files: missing required Taildrop capability")

	case ipnstate.TaildropTargetOffline:
		// Don't gate on the server-reported Online bit (which lags reality
		// and isn't always accurate). runCp probes reachability itself with
		// TSMP pings.
		return foundPeer.ID, isOffline, nil

	case ipnstate.TaildropTargetNoPeerInfo:
		return "", isOffline, errors.New("cannot send files: invalid or unrecognized peer")

	case ipnstate.TaildropTargetUnsupportedOS:
		return "", isOffline, errors.New("cannot send files: target's OS does not support Taildrop")

	case ipnstate.TaildropTargetNoPeerAPI:
		return "", isOffline, errors.New("cannot send files: target is not advertising a file sharing API")

	case ipnstate.TaildropTargetOwnedByOtherUser:
		return "", isOffline, errors.New("cannot send files: peer is owned by a different user")

	case ipnstate.TaildropTargetUnknown:
		fallthrough
	default:
		return "", isOffline, fmt.Errorf("cannot send files: unknown or indeterminate reason")
	}
}

const maxSniff = 4 << 20

func ext(b []byte) string {
	if len(b) < maxSniff && utf8.Valid(b) {
		return ".txt"
	}
	if exts, _ := mime.ExtensionsByType(http.DetectContentType(b)); len(exts) > 0 {

View on GitHub (pinned to cfe32b8be6)

When it happens

Trigger: Thrown at cmd/tailscale/cli/file.go:509 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of tailscale/tailscale@cfe32b8be6 (2026-08-15). Data as JSON: /api/errors/7f2cd855d729f1ff. Report an issue: GitHub.