go-delve/delve · error

could not determine path for module %s (got %q and %q)

Error message

could not determine path for module %s (got %q and %q)

What it means

While building the module substitute-path map, 'go list' output assigned two different directories to the same module path after trimming the expected number of path elements, so the mapping is ambiguous and MakeGuessSusbtitutePathIn aborts with this error. Indicates module metadata that does not match the on-disk layout.

Source

Thrown at service/rpc2/client.go:669

		if e.Module == nil {
			continue
		}
		if !strings.HasPrefix(e.ImportPath, e.Module.Path) {
			continue
		}
		pkgWithoutModule := e.ImportPath[len(e.Module.Path):]
		elems := 0
		for _, c := range pkgWithoutModule {
			if c == '/' {
				elems++
			}
		}
		dir := e.Dir
		for i := 0; i < elems; i++ {
			dir = filepath.Dir(dir)
		}
		if mod2dir[e.Module.Path] != "" && mod2dir[e.Module.Path] != dir {
			return nil, fmt.Errorf("could not determine path for module %s (got %q and %q)", e.Module.Path, mod2dir[e.Module.Path], dir)
		}
		mod2dir[e.Module.Path] = dir
		if e.Name == "main" {
			if importPathOfMainPackage != "" && importPathOfMainPackage != e.ImportPath {
				importPathOfMainPackageOk = false
			}
			importPathOfMainPackage = e.ImportPath
		}
	}
	buf, err = exec.Command("go", "env", "GOROOT").Output()
	if err != nil {
		return nil, err
	}
	clientGoroot := strings.TrimSpace(string(buf))
	if !importPathOfMainPackageOk {
		// There were multiple main packages
		importPathOfMainPackage = ""
	}

View on GitHub (pinned to a23773e6c3)

Solutions

1. Clean the module cache: go clean -modcache, then rebuild
2. Remove or fix conflicting replace directives in go.mod
3. Ensure the program is built with the same module layout you debug against
4. Fall back to configuring substitutePath manually in your client instead of guessing

Example fix

// before
sub, err := client.MakeGuessSusbtitutePathIn() // ambiguous module path
// after
// fix go.mod replace directives, then:
sub, err := client.MakeGuessSusbtitutePathIn()
// or set client.SubstitutePath manually

// inspect module list for duplicates before trusting the mapping
cmd := exec.Command("go", "list", "-m", "all")
out, err := cmd.Output()
hasDup := func(mod string) bool { return strings.Count(string(out), mod) > 1 }

sub, err := client.MakeGuessSusbtitutePathIn()
if err != nil && strings.Contains(err.Error(), "could not determine path for module") {
    // use explicit client.SubstitutePath entries instead of guessed ones
}

When it happens

Trigger: GuessSubstitutePathIn RPC where a module appears multiple times in 'go list --json all' output with conflicting computed Dir values (after filepath.Dir applied elems times).

Common situations: Vendor directories mixed with module cache copies; replace directives pointing at local forks; monorepo layouts where module depth (elems) doesn't match directory structure; stale module cache.

Related errors

• error running go list %v: output %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/c57f35ff2dfa5ccf. Report an issue: GitHub.