What causes "unknown browser kind: %d" in moonD4rk/HackBrowserData?

Use a Kind constant defined by the browser package instead of a raw integer.

unknown browser kind: %d

Error message

unknown browser kind: %d

What it means

newBrowser builds a browser instance from a Config whose Kind field must be one of the known browser kinds. If Kind holds a value the switch doesn't handle (not a recognized Chromium/Firefox browser), construction fails with this error naming the numeric kind. It indicates a Config assembled with an invalid or out-of-range Kind.

Source

Thrown at browser/browser.go:160

			return nil, err
		}
		if b == nil {
			return nil, nil
		}
		return b, nil

	case types.Safari:
		b, err := safari.NewBrowser(cfg)
		if err != nil {
			return nil, err
		}
		if b == nil {
			return nil, nil
		}
		return b, nil

	default:
		return nil, fmt.Errorf("unknown browser kind: %d", cfg.Kind)
	}
}

// ListBrowsers returns sorted keys of all platform browsers.
func ListBrowsers() []string {
	var l []string
	for _, cfg := range platformBrowsers() {
		l = append(l, cfg.Key)
	}
	sort.Strings(l)
	return l
}

// Names returns a pipe-separated list of browser keys for CLI help text.
func Names() string {
	return strings.Join(ListBrowsers(), "|")
}

View on GitHub (pinned to 0503d04d7a)

Solutions

Use a Kind constant defined by the browser package instead of a raw integer.
Check the numeric value against the browser kind enum in browser/browser.go and pick a supported one.
If the browser genuinely isn't supported, don't construct a Config for it — filter it out of discover results.
Update the library if a new browser kind needs support in the switch.

Example fix

// before
cfg := browser.Config{Kind: 99, Name: "mybrowser"}
b, err := browser.NewBrowser(cfg)
// after
cfg := browser.Config{Kind: browser.Chrome, Name: "chrome"}
b, err := browser.NewBrowser(cfg)

Defensive patterns

Strategy: validation

Validate before calling

switch cfg.Kind {
case browser.Chrome, browser.Firefox /* supported kinds */ :
    // ok
default:
    return fmt.Errorf("unsupported browser kind %d", cfg.Kind)
}

Try / catch

b, err := browser.NewBrowser(cfg)
if err != nil && strings.HasPrefix(err.Error(), "unknown browser kind") {
    return nil, fmt.Errorf("kind %d unsupported in this build: %w", cfg.Kind, err)
}

Prevention

Only use exported Kind constants from the browser package.
Filter discovered configs to supported kinds before constructing.
Keep Config construction centralized so raw integers never reach Kind.

When it happens

Trigger: Calling newBrowser (directly or via discoverFromConfigs or BuildFromDump) with a Config whose Kind is an unregistered browser kind value — falls into the switch's default branch.

Common situations: Constructing browser.Config manually with a guessed Kind constant, a dump file declaring an unrecognized browser kind, or an enum added upstream but not handled in this build's switch.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

AI-assisted analysis of moonD4rk/HackBrowserData@0503d04d7a (2026-09-06). Data as JSON: /api/errors/5f7d0561ffd258f8. Report an issue: GitHub.