hashicorp/packer · error

malformed manifest.json for version

Error message

malformed manifest.json for version %s: %w

What it means

resolveProtocolVersion downloads a plugin version's manifest.json and parses it to cache the plugin protocol version used by Validate. This error fires when the fetched manifest is unparseable or structurally invalid (e.g. missing/ill-formed checksum entries), wrapped with the underlying cause. It usually indicates a corrupted or non-standard release published for that plugin version; reinstall the plugin or use a different version.

Solutions

1. Fix or replace the mirror's manifest.json with the file published on releases.hashicorp.com
2. Bypass the mirror and install from the official release endpoint

When it happens

Trigger: Thrown at packer/plugin-getter/remote/getter.go:203 when the library encounters an invalid state.

Common situations: See trigger scenarios.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

AI-assisted analysis of hashicorp/packer@eb36e3c3e4 (2026-09-05). Data as JSON: /api/errors/195985cd5b195f81. Report an issue: GitHub.

Appendix: source

Thrown at packer/plugin-getter/remote/getter.go:203

			version, idx.pluginType, g.BaseURL, dir)
	}
	return idx, g.BaseURL + "/" + dir + "/" + version, nil
}

// resolveProtocolVersion reads the plugin protocol version from a version's
// manifest.json and caches it for Validate.
func (g *Getter) resolveProtocolVersion(versionURL, pluginType, version string) error {
	if _, ok := g.protVersions[version]; ok {
		return nil
	}
	data, err := g.fetch(versionURL + "/" + pluginType + "_" + version + "_manifest.json")
	if err != nil {
		return fmt.Errorf(
			"%w\nThe checksum entries of this version carry no plugin protocol version in their names, so the mirrored version must include its manifest.json, as published on releases.hashicorp.com", err)
	}
	var meta plugingetter.ManifestMeta
	if err := json.Unmarshal(data, &meta); err != nil {
		return fmt.Errorf("malformed manifest.json for version %s: %w", version, err)
	}
	if meta.Metadata.ProtocolVersion == "" {
		return fmt.Errorf("manifest.json for version %s declares no protocol_version", version)
	}
	if g.protVersions == nil {
		g.protVersions = map[string]string{}
	}
	g.protVersions[version] = "x" + meta.Metadata.ProtocolVersion
	return nil
}

func (g *Getter) Get(what string, opts plugingetter.GetOptions) (io.ReadCloser, error) {
	log.Printf("[TRACE] Getting %s of %s plugin from %s", what, opts.PluginRequirement.Identifier, g.Name)

	switch what {
	case "releases":
		idx, _, err := g.loadIndex(opts)
		if err != nil {

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