go-delve/delve · error

error running go list %v: output %q

Error message

error running go list %v: output %q

What it means

MakeGuessSusbtitutePathIn runs 'go list --json all' to build a module-to-directory mapping for substitute-path guessing; if the command fails, the error (including the captured output) is returned wrapped in this message. Typically means the Go toolchain is missing or the module graph is broken.

Source

Thrown at service/rpc2/client.go:639

type goListEntry struct {
	Dir        string
	ImportPath string
	Name       string
	Module     *goListModule
}

type goListModule struct {
	Path string
}

// MakeGuessSusbtitutePathIn returns a mapping from modules to client
// directories using "go list".
func MakeGuessSusbtitutePathIn() (*api.GuessSubstitutePathIn, error) {
	cmd := exec.Command("go", "list", "--json", "all")
	buf, err := cmd.Output()
	if err != nil {
		return nil, fmt.Errorf("error running go list %v: output %q", err, string(buf))
	}
	importPathOfMainPackage := ""
	importPathOfMainPackageOk := true
	mod2dir := make(map[string]string)
	d := json.NewDecoder(bytes.NewReader(buf))
	for d.More() {
		var e goListEntry
		err := d.Decode(&e)
		if err != nil {
			return nil, err
		}
		if e.Module == nil {
			continue
		}
		if !strings.HasPrefix(e.ImportPath, e.Module.Path) {
			continue
		}
		pkgWithoutModule := e.ImportPath[len(e.Module.Path):]

View on GitHub (pinned to a23773e6c3)

Solutions

1. Ensure 'go' is installed and on PATH: run 'go version' in the target's working directory
2. Run 'go list --json all' manually in the program directory to see the real error
3. Run 'go mod tidy' to fix inconsistent module requirements
4. Check GOPROXY/GOFLAGS environment variables and network access

Example fix

// before
sub, err := client.MakeGuessSusbtitutePathIn() // fails: go not found
// after (ensure env)
cmd.Env = append(os.Environ(), "PATH="+goBinDir+":"+os.Getenv("PATH"))
sub, err := client.MakeGuessSusbtitutePathIn()

if _, err := exec.LookPath("go"); err != nil { return fmt.Errorf("go toolchain required") }
if _, err := os.Stat("go.mod"); err != nil { return fmt.Errorf("run in module directory") }

sub, err := client.MakeGuessSusbtitutePathIn()
if err != nil && strings.Contains(err.Error(), "error running go list") {
    // fall back to manually configured substitute paths
}

When it happens

Trigger: Calling the GuessSubstitutePathIn RPC (or the client helper) in an environment where exec.Command("go","list","--json","all") exits non-zero.

Common situations: go not installed or not on PATH in the debug session; go.mod/go.sum inconsistent (missing requirements); GOFLAGS/GOPROXY misconfigured; network blocked during module download.

Related errors

• could not determine path for module %s (got %q and %q)
• too many arguments to "config substitutePath"
• could not find rule for %q
• could not find rule for %q
• Process %d has exited with status %d

AI-assisted analysis of go-delve/delve@a23773e6c3 (2026-08-31). Data as JSON: /api/errors/8b1e963722dd4c34. Report an issue: GitHub.