What causes "cannot use multiple consecutive dashes" in hashicorp/packer?

Remove or replace consecutive dashes in the plugin source component with single dashes or other allowed characters

cannot use multiple consecutive dashes

Error message

cannot use multiple consecutive dashes

What it means

ParsePluginPart normalizes one component (host, org, type, or name) of a Packer plugin source address using IDNA lookup. It rejects strings containing '--' because consecutive dashes look confusing and would trigger the IDNA 'xn--' punycode interpretation path. This is a deliberate validation rule, not a bug.

Solutions

Remove or replace consecutive dashes in the plugin source component with single dashes or other allowed characters
Use only letters, digits, and single dashes, with no leading/trailing dashes
If the real repository name contains '--', reference it via a different identifier or rename the repository/plugin

Example fix

// before
source "github.com/hashicorp/packer--plugin--amazon"
// after
source "github.com/hashicorp/packer-plugin-amazon"

Defensive patterns

Strategy: validation

Validate before calling

func validPluginPart(s string) bool { return !strings.Contains(s, "--") }

Type guard

func isSafePluginPart(s string) bool { return s != "" && !strings.Contains(s, "--") }

Prevention

Lint required_plugins source strings for '--' before running packer init
Derive plugin types from repo names by replacing separators with single dashes
Never copy repository names with double dashes directly into sources

When it happens

Trigger: Calling ParsePluginPart (directly, or indirectly via ParsePluginSourceString or checkPluginNameNormalized) with a string containing two or more consecutive dashes, e.g. 'github.com/hashicorp/packer--plugin--foo'.

Common situations: Typos in plugin source addresses in required_plugins blocks; users copying repository names like 'packer-plugin-some--name'; attempts to encode separators with dashes; punycode/internationalized domain names containing '--'.

Related errors

AI-assisted analysis of hashicorp/packer@eb36e3c3e4 (2026-09-05). Data as JSON: /api/errors/29e0d8b76cc7b923. Report an issue: GitHub.

Appendix: source

Thrown at hcl2template/addrs/plugin.go:84

	// We're going to process the given name using the same "IDNA" library we
	// use for the hostname portion, since it already implements the case
	// folding rules we want.
	//
	// The idna library doesn't expose individual label parsing directly, but
	// once we've verified it doesn't contain any dots we can just treat it
	// like a top-level domain for this library's purposes.
	if strings.ContainsRune(given, '.') {
		return "", fmt.Errorf("dots are not allowed")
	}

	// We don't allow names containing multiple consecutive dashes, just as
	// a matter of preference: they look confusing, or incorrect.
	// This also, as a side-effect, prevents the use of the "punycode"
	// indicator prefix "xn--" that would cause the IDNA library to interpret
	// the given name as punycode, because that would be weird and unexpected.
	if strings.Contains(given, "--") {
		return "", fmt.Errorf("cannot use multiple consecutive dashes")
	}

	result, err := idna.Lookup.ToUnicode(given)
	if err != nil {
		return "", fmt.Errorf("must contain only letters, digits, and dashes, and may not use leading or trailing dashes: %w", err)
	}

	return result, nil
}

// IsPluginPartNormalized compares a given string to the result of ParsePluginPart(string)
func IsPluginPartNormalized(str string) (bool, error) {
	normalized, err := ParsePluginPart(str)
	if err != nil {
		return false, err
	}
	if str == normalized {
		return true, nil

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