go-delve/delve · error

lldb backend not supported on Windows

Error message

lldb backend not supported on Windows

What it means

ErrUnsupportedOS is a sentinel error returned by LLDBLaunch and LLDBAttach in the gdbserial backend when the host OS is Windows. The LLDB-based backend relies on lldb-server, which is not supported on Windows, so any attempt to use the lldb backend there fails immediately with this error.

Source

Thrown at pkg/proc/gdbserial/gdbserver.go:443

}

func canUnmaskSignals(debugServerExecutable string) bool {
	checkCanUnmaskSignalsOnce.Do(func() {
		buf, _ := exec.Command(debugServerExecutable, "--unmask-signals").CombinedOutput()
		canUnmaskSignalsCached = !strings.Contains(string(buf), "unrecognized option")
	})
	return canUnmaskSignalsCached
}

// commandLogger is a wrapper around the exec.Command() function to log the arguments prior to
// starting the process
func commandLogger(binary string, arguments ...string) *exec.Cmd {
	logflags.GdbWireLogger().Debugf("executing %s %v", binary, arguments)
	return exec.Command(binary, arguments...)
}

// ErrUnsupportedOS is returned when trying to use the lldb backend on Windows.
var ErrUnsupportedOS = errors.New("lldb backend not supported on Windows")

func getLdEnvVars() []string {
	var result []string

	environ := os.Environ()
	for i := range environ {
		if strings.HasPrefix(environ[i], "LD_") ||
			strings.HasPrefix(environ[i], "DYLD_") {
			result = append(result, "-e", environ[i])
		}
	}

	return result
}

// LLDBLaunch starts an instance of lldb-server and connects to it, asking
// it to launch the specified target program with the specified arguments
// (cmd) on the specified directory wd.

View on GitHub (pinned to a23773e6c3)

Solutions

1. Use the native backend instead: dlv debug/exec/attach --backend=native (the default on Windows).
2. Remove explicit --backend=lldb from scripts/IDE launch configs on Windows.
3. If you need LLDB specifically, run delve inside WSL or a Linux/macOS environment.
4. Guard code with runtime.GOOS checks before choosing the backend.

Example fix

// before
dlv exec ./app.exe --backend=lldb
// after
dlv exec ./app.exe --backend=native

if runtime.GOOS == "windows" && backend == "lldb" {
    return errors.New("lldb backend is unsupported on Windows; use native")
}

if errors.Is(err, gdbserial.ErrUnsupportedOS) {
    // fall back to native backend
}

When it happens

Trigger: Calling gdbserial.LLDBLaunch or gdbserial.LLDBAttach on a Windows host (i.e. selecting the lldb backend, e.g. via 'dlv exec --backend=lldb' or debugging a binary compiled with cgo/lldb config).

Common situations: Windows users running 'dlv debug --backend=lldb', IDE configs defaulting to the lldb backend, or following documentation for macOS/Linux that does not apply on Windows.

Related errors

• unknown debug event code: %d
• backend does not support function calls
• could not connect
• eBPF is disabled
• VirtualQueryEx wrapped around the address space or stuck

AI-assisted analysis of go-delve/delve@a23773e6c3 (2026-08-31). Data as JSON: /api/errors/dedb5957b7417015. Report an issue: GitHub.