golang/go · error

%s: unknown vcs %q

Error message

%s: unknown vcs %q

What it means

The matched meta import declares a VCS kind that is neither 'mod' nor matched by vcsByCmd against vcsList (git, hg, svn, fossil, bzr). vcsByCmd returned nil. The %s is resp.URL; %q is the unrecognized VCS string.

Source

Thrown at src/cmd/go/internal/vcs/vcs.go:1062

		if err != nil || mmi != metaImport2 {
			return nil, fmt.Errorf("%s and %s disagree about go-import for %s", resp.URL, url, mmi.Prefix)
		}
	}

	if err := validateRepoSubDir(mmi.SubDir); err != nil {
		return nil, fmt.Errorf("%s: invalid subdirectory %q: %v", resp.URL, mmi.SubDir, err)
	}

	if err := validateRepoRoot(mmi.RepoRoot); err != nil {
		return nil, fmt.Errorf("%s: invalid repo root %q: %v", resp.URL, mmi.RepoRoot, err)
	}
	var vcs *Cmd
	if mmi.VCS == "mod" {
		vcs = vcsMod
	} else {
		vcs = vcsByCmd(mmi.VCS)
		if vcs == nil {
			return nil, fmt.Errorf("%s: unknown vcs %q", resp.URL, mmi.VCS)
		}
	}

	if err := checkGOVCS(vcs, mmi.Prefix); err != nil {
		return nil, err
	}

	repoURL, ok := interceptVCSTest(mmi.RepoRoot, vcs, security)
	if !ok {
		repoURL = mmi.RepoRoot
	}
	rr := &RepoRoot{
		Repo:     repoURL,
		Root:     mmi.Prefix,
		SubDir:   mmi.SubDir,
		IsCustom: true,
		VCS:      vcs,
	}

View on GitHub (pinned to b6b368adc5)

Solutions

1. Set the meta tag VCS to one of: git, hg, svn, fossil, mod
2. Switch the module to a supported VCS or serve it through a Go module proxy

var allowedVCS = map[string]bool{"git": true, "hg": true, "svn": true, "fossil": true, "mod": true}
func validVCS(v string) bool { return allowedVCS[v] }

When it happens

Trigger: A go-import meta tag lists e.g. 'github', 'perforce', or 'cvs' as the VCS field.

Common situations: Typo in the meta tag's VCS field; vanity server template bug; an unsupported/bzr-only host after bzr support was deprecated.

Related errors

• parse %s: %v
• parse %s: no go-import meta tags (%s)
• %s and %s disagree about go-import for %s
• %s: invalid subdirectory %q: %v
• %s: invalid repo root %q: %v

AI-assisted analysis of golang/go@b6b368adc5 (2026-08-12). Data as JSON: /api/errors/197f063bd0975e6a. Report an issue: GitHub.