hashicorp/packer · error

Error reading checksum file: %s

Error message

Error reading checksum file: %s

What it means

When parsing GitHub's checksum/tag file line by line, a read error other than io.EOF aborts parsing with this error. It wraps the underlying reader failure, so the checksum file content could not be fully retrieved from the network.

Source

Thrown at packer/plugin-getter/github/getter.go:61

	Versions map[string]PluginVersion `json:"versions"`
}

type PluginVersion struct {
	Name    string `json:"name"`
	Version string `json:"version"`
}

func TransformChecksumStream() func(in io.ReadCloser) (io.ReadCloser, error) {
	return func(in io.ReadCloser) (io.ReadCloser, error) {
		defer in.Close()
		rd := bufio.NewReader(in)
		buffer := bytes.NewBufferString("[")
		json := json.NewEncoder(buffer)
		for i := 0; ; i++ {
			line, err := rd.ReadString('\n')
			if err != nil {
				if err != io.EOF {
					return nil, fmt.Errorf(
						"Error reading checksum file: %s", err)
				}
				break
			}
			parts := strings.Fields(line)
			switch len(parts) {
			case 2: // nominal case
				checksumString, checksumFilename := parts[0], parts[1]

				if i > 0 {
					_, _ = buffer.WriteString(",")
				}
				if err := json.Encode(struct {
					Checksum string `json:"checksum"`
					Filename string `json:"filename"`
				}{
					Checksum: checksumString,
					Filename: checksumFilename,

View on GitHub (pinned to eb36e3c3e4)

Solutions

1. Retry `packer init` — this is typically a transient network error.
2. Check proxy settings (HTTP_PROXY/HTTPS_PROXY) and corporate TLS interception.
3. Verify connectivity to github.com/objects.githubusercontent.com.
4. If persistent, download the checksum file manually and use a local file source.

resp, err := http.Get(checksumURL)
if err == nil && resp.StatusCode != http.StatusOK {
    return fmt.Errorf("checksum endpoint returned %d", resp.StatusCode)
}

for attempt := 0; attempt < 3; attempt++ {
    err := installPlugins()
    if err == nil || !isNetworkErr(err) { break }
    time.Sleep(time.Duration(1<<attempt) * time.Second)
}

When it happens

Trigger: Streaming the checksum file from a GitHub release URL and the HTTP body read fails with a non-EOF error: connection reset, TLS error, or proxy interruption — anything where rd.ReadString('\n') returns err != nil && err != io.EOF.

Common situations: Corporate proxy or firewall cutting the connection; GitHub rate-limiting or transient 5xx behind a streaming reader; flaky VPN/network during `packer init`.

Related errors

• empty response body for %s
• failed to download release checksums: %w
• request GitHub OIDC token: %w
• Failed to hash: %s
• transformVersionStream got nil body

AI-assisted analysis of hashicorp/packer@eb36e3c3e4 (2026-09-05). Data as JSON: /api/errors/24ae9d1171bdf94a. Report an issue: GitHub.