parsing go.mod: module declares its path as: %s bu

Error message

parsing go.mod:
	module declares its path as: %s
	        but was required as: %s

What it means

Returned while building a module graph summary (modfile.go:638) when the module directive inside a fetched dependency's go.mod declares a different path than the path it was required under, and also different from any replacement target. The toolchain refuses to use a module whose self-declared identity disagrees with how it was imported, because import resolution within that module would be ambiguous.

Source

Thrown at src/cmd/go/internal/modload/modfile.go:638

		// matching module paths. Anything goes.
		//
		// TODO(bcmills): Remove this special-case, update tests, and add a
		// release note.
	} else {
		if summary.module.Path == "" {
			return nil, module.VersionError(actual, errors.New("parsing go.mod: missing module line"))
		}

		// In theory we should only allow mpath to be unequal to m.Path here if the
		// version that we fetched lacks an explicit go.mod file: if the go.mod file
		// is explicit, then it should match exactly (to ensure that imports of other
		// packages within the module are interpreted correctly). Unfortunately, we
		// can't determine that information from the module proxy protocol: we'll have
		// to leave that validation for when we load actual packages from within the
		// module.
		if mpath := summary.module.Path; mpath != m.Path && mpath != actual.Path {
			return nil, module.VersionError(actual,
				fmt.Errorf("parsing go.mod:\n"+
					"\tmodule declares its path as: %s\n"+
					"\t        but was required as: %s", mpath, m.Path))
		}
	}

	for _, mainModule := range ld.MainModules.Versions() {
		if index := ld.MainModules.Index(mainModule); index != nil && len(index.exclude) > 0 {
			// Drop any requirements on excluded versions.
			// Don't modify the cached summary though, since we might need the raw
			// summary separately.
			haveExcludedReqs := false
			for _, r := range summary.require {
				if index.exclude[r] {
					haveExcludedReqs = true
					break
				}
			}
			if haveExcludedReqs {

View on GitHub (pinned to b6b368adc5)

Solutions

Update the require/replace to the path the module actually declares (the value shown as 'module declares its path as').
If using a replace to a local directory, fix the module directive in that directory's go.mod to match the required path.
Clear the corrupted entry from the module cache and re-download: 'go clean -modcache && go mod download'.
Report to the module author if a published version genuinely ships the wrong module path.

Example fix

// before
go.mod requires: require example.com/old v1.0.0
// fetched go.mod says: module example.com/new
// error: parsing go.mod: module declares its path as: example.com/new
//                      but was required as: example.com/old

// after
require example.com/new v1.0.0

Defensive patterns

Strategy: validation

Validate before calling

// When using a replace target, verify its go.mod module line matches the required path:
//   repMod := exec.Command("go", "mod", "edit", "-print").run-in-replace-dir
//   require repMod == requiredPath before committing the replace directive.

Type guard

func modulePathMatchesRequired(f *modfile.File, required string) bool {
    return f != nil && f.Module != nil && (f.Module.Mod.Path == required)
}

Prevention

After renaming a module, update every require and the module's own module directive in lockstep.
For local replacements, keep the replaced directory's module line equal to the required path.
Run 'go list -m all' in CI to surface path mismatches early.

When it happens

Trigger: A go.mod fetched for path A declares 'module B'; the requirement pointed at A but the downloaded artifact is actually B; a misconfigured module proxy or fork served the wrong go.mod; a replace directive targets a directory whose go.mod names a different module.

Common situations: A dependency was renamed/moved but an old require still references the former path; a fork served under the original path; a vendored or replaced local module whose go.mod module line was not updated after a rename.

Related errors

AI-assisted analysis of golang/go@b6b368adc5 (2026-08-12). Data as JSON: /api/errors/1c4cc084fb5c1119. Report an issue: GitHub.