golang/go · error

invalid module path %q

Error message

invalid module path %q

What it means

newCodeRepo calls module.SplitPathVersion on the module path; if it returns ok==false the path cannot be decomposed into a prefix and version suffix, so the path is syntactically invalid. The %q is the offending path.

Source

Thrown at src/cmd/go/internal/modfetch/coderepo.go:72

	// pseudoMajor is the major version prefix to require when generating
	// pseudo-versions for this module, derived from the module path. pseudoMajor
	// is empty if the module path does not include a version suffix (that is,
	// accepts either v0 or v1).
	pseudoMajor string
}

// newCodeRepo returns a Repo that reads the source code for the module with the
// given path, from the repo stored in code.
// codeRoot gives the import path corresponding to the root of the repository,
// and subdir gives the subdirectory within the repo containing the module.
// If subdir is empty, the module is at the root of the repo.
func newCodeRepo(code codehost.Repo, codeRoot, subdir, path string) (Repo, error) {
	if !hasPathPrefix(path, codeRoot) {
		return nil, fmt.Errorf("mismatched repo: found %s for %s", codeRoot, path)
	}
	pathPrefix, pathMajor, ok := module.SplitPathVersion(path)
	if !ok {
		return nil, fmt.Errorf("invalid module path %q", path)
	}
	if codeRoot == path {
		pathPrefix = path
	}
	pseudoMajor := module.PathMajorPrefix(pathMajor)

	// Compute codeDir = bar, the subdirectory within the repo
	// corresponding to the module root.
	//
	// At this point we might have:
	//	path = github.com/rsc/foo/bar/v2
	//	codeRoot = github.com/rsc/foo
	//	pathPrefix = github.com/rsc/foo/bar
	//	pathMajor = /v2
	//	pseudoMajor = v2
	//
	// which gives
	//	codeDir = bar

View on GitHub (pinned to b6b368adc5)

Solutions

1. Print go.mod and verify the module path follows the Go module path rules (lowercase, dot-separated, optional /vN suffix where N>=2).
2. Correct the module path in the upstream go.mod and re-tag.
3. Inspect the go-import meta tag and ensure the advertised path is well-formed.
4. Use `go mod edit -module=<correct path>` to fix a local module declaration.

Example fix

// before
module github.com/User/Repo  // uppercase letters are invalid
// error: invalid module path "github.com/User/Repo"

// after
module github.com/user/repo

func modulePathValid(path string) bool {
    _, _, ok := module.SplitPathVersion(path)
    return ok
}

func isValidModulePath(p string) bool {
    if p == "" { return false }
    if !utf8.ValidString(p) { return false }
    if strings.ContainsAny(p, "\\ABCDEFGHIJKLMNOPQRSTUVWXYZ") { return false }
    _, _, ok := module.SplitPathVersion(p)
    return ok
}

When it happens

Trigger: module.SplitPathVersion fails — path contains invalid version characters, an unparseable /vN suffix, escapes, or control characters. Indicates a corrupt go.mod, replace directive, or vanity meta tag emitting a malformed path.

Common situations: A go.mod with a typo'd module path (e.g. trailing slash, uppercase letters, '/v' followed by non-digit); a vanity server emitting a path with disallowed characters; a replace directive pointing at a relative path leaking into module resolution.

Related errors

• %s has malformed module path %q%s at revision %s
• invalid %s path: %v
• invalid version interval: %q
• non-semver module version %q
• invalid version %q

AI-assisted analysis of golang/go@b6b368adc5 (2026-08-12). Data as JSON: /api/errors/dfaf4b550bdb321b. Report an issue: GitHub.