k3s-io/k3s · critical

tar error: %v

Error message

tar error: %v

What it means

After the zstd stream is opened, untar iterates tar entries; any error from tar.Reader.Next other than io.EOF (corrupt tar structure, truncated archive mid-entry, checksum mismatch in the stream) is logged as 'tar reading error' and returned wrapped as 'tar error'. Like the zstd error above, this occurs while extracting the embedded data-dir payload during first boot or upgrade.

Source

Thrown at pkg/untar/untar.go:56

		if err != nil {
			logrus.Printf("error extracting tarball into %s after %d files, %d dirs, %v: %v", dir, nFiles, len(madeDir), td, err)
		}
	}()
	zr, err := zstd.NewReader(r, zstd.WithDecoderMaxMemory(tarfile.MaxDecoderMemory))
	if err != nil {
		return fmt.Errorf("error extracting zstd-compressed body: %v", err)
	}
	defer zr.Close()
	tr := tar.NewReader(zr)
	loggedChtimesError := false
	for {
		f, err := tr.Next()
		if err == io.EOF {
			break
		}
		if err != nil {
			logrus.Printf("tar reading error: %v", err)
			return fmt.Errorf("tar error: %v", err)
		}
		if !validRelPath(f.Name) {
			return fmt.Errorf("tar contained invalid name error %q", f.Name)
		}
		rel := filepath.FromSlash(f.Name)
		abs := filepath.Join(dir, rel)

		fi := f.FileInfo()
		mode := fi.Mode()
		switch {
		case mode.IsRegular():
			// Make the directory. This is redundant because it should
			// already be made by a directory entry in the tar
			// beforehand. Thus, don't check for errors; the next
			// write will fail with the same error.
			dir := filepath.Dir(abs)
			if !madeDir[dir] {
				if err := os.MkdirAll(filepath.Dir(abs), 0755); err != nil {

View on GitHub (pinned to 6ba341e396)

Solutions

1. Re-download the k3s binary and verify its sha256 checksum against the official checksums file.
2. Check free disk space and dmesg for filesystem errors on the data-dir volume; free space and retry.
3. Remove leftover '<dir>-tmp' extraction directories (they are auto-removed, but verify) and restart k3s to re-extract cleanly.
4. If self-built, rebuild ensuring the embedded tarball asset is generated and embedded intact.

Example fix

# before: truncated binary
ls -l k3s  # size smaller than published
./k3s server  # tar error: unexpected EOF

# after
sha256sum -c sha256sums.txt && ./k3s server

// Same pre-flight as 198: binary checksum plus free-space check on data dir
if !checksumMatches("k3s", wantSHA) { log.Fatal("redownload k3s") }
if free, _ := diskFree(dataDir); free < minSpace { log.Fatal("insufficient disk for extraction") }

When it happens

Trigger: untar's tr.Next() fails mid-iteration: the embedded tarball is truncated (binary cut short), an entry header is corrupt, or the underlying reader errors partway. The deferred log line reports how many files/directories were extracted before the failure, localizing the truncation point.

Common situations: Partially downloaded or corrupted k3s binaries (most common); disk filling up while writing extracted files can surface as reader/writer errors here; binaries repacked or stripped in ways that damaged the embedded blob.

Related errors

• error extracting zstd-compressed body: %v
• failed to verify directory %s
• no entries found in %s
• failed %d hash verifications
• failed %d link verifications

AI-assisted analysis of k3s-io/k3s@6ba341e396 (2026-08-15). Data as JSON: /api/errors/59b606524018cf38. Report an issue: GitHub.