golang/go · error · DownloadDirPartialError

not completely extracted

Error message

not completely extracted

What it means

A `.partial` marker file is created at the start of a module download and removed once the zip is fully extracted. Its presence next to the module directory means extraction was interrupted, so DownloadDir returns a DownloadDirPartialError rather than a half-extracted directory.

Source

Thrown at src/cmd/go/internal/modfetch/cache.go:113

	// Check whether the directory itself exists.
	dir := filepath.Join(cfg.GOMODCACHE, enc+"@"+encVer)
	if fi, err := os.Stat(dir); os.IsNotExist(err) {
		return dir, err
	} else if err != nil {
		return dir, &DownloadDirPartialError{dir, err}
	} else if !fi.IsDir() {
		return dir, &DownloadDirPartialError{dir, errors.New("not a directory")}
	}

	// Check if a .partial file exists. This is created at the beginning of
	// a download and removed after the zip is extracted.
	partialPath, err := CachePath(ctx, m, "partial")
	if err != nil {
		return dir, err
	}
	if _, err := os.Stat(partialPath); err == nil {
		return dir, &DownloadDirPartialError{dir, errors.New("not completely extracted")}
	} else if !os.IsNotExist(err) {
		return dir, err
	}

	// Special case: ziphash is not required for the golang.org/fips140 module,
	// because it is unpacked from a file in GOROOT, not downloaded.
	// We've already checked that it's not a partial unpacking, so we're happy.
	if m.Path == "golang.org/fips140" {
		return dir, nil
	}

	// Check if a .ziphash file exists. It should be created before the
	// zip is extracted, but if it was deleted (by another program?), we need
	// to re-calculate it. Note that checkMod will repopulate the ziphash
	// file if it doesn't exist, but if the module is excluded by checks
	// through GONOSUMDB or GOPRIVATE, that check and repopulation won't happen.
	ziphashPath, err := CachePath(ctx, m, "ziphash")
	if err != nil {

View on GitHub (pinned to b6b368adc5)

Solutions

  1. Run `go mod download <module>` again; the go command will detect the partial state and retry extraction.
  2. If retries fail, run `go clean -modcache` and re-download from scratch.
  3. Free disk space if the original extraction failed due to ENOSPC, then retry.
Defensive patterns

Strategy: retry

Validate before calling

// Detect the partial marker:
//   if _, err := os.Stat(filepath.Join(dir, ".partial")); err == nil {
//     // incomplete extraction; remove and re-download
//   }

Try / catch

// On *modfetch.DownloadDirPartialError due to .partial, delete the
// module dir and its .partial file, then `go mod download` again.

Prevention

When it happens

Trigger: DownloadDir finds a `.partial` file in the cache alongside the module's extracted directory, indicating the download/extract did not finish.

Common situations: go mod download killed (Ctrl-C, OOM) mid-extraction; disk full during extraction; a concurrent go process died holding the partial marker; system crash or power loss during download.

Related errors

AI-assisted analysis of golang/go@b6b368adc5 (2026-08-12). Data as JSON: /api/errors/3c29af32d70c30a7. Report an issue: GitHub.