BCUninstaller/Bulk-Crap-Uninstaller · error · ArgumentException

Path root is invalid or missing

Error message

Path root is invalid or missing

What it means

Thrown by GetRootHive when the parsed root segment of a registry path does not match any of the supported hive aliases (HKLM, HKCR, HKCU, HKU/HKUS, HKCC, or their HKEY_* long forms). The library refuses to guess a hive, so any unrecognized leading token is treated as a malformed path. It is an ArgumentException, raised after GetKeyRoot has already normalized the leading segment to upper-case.

Source

Thrown at source/KlocTools/Tools/RegistryTools.cs:249

                case HklmShortRootName:
                    rootKey = Registry.LocalMachine;
                    break;
                case HkcrShortRootName:
                    rootKey = Registry.ClassesRoot;
                    break;
                case HkcuShortRootName:
                    rootKey = Registry.CurrentUser;
                    break;
                case HkuShortRootName:
                case HkuShortRootName2:
                    rootKey = Registry.Users;
                    break;
                case HkccShortRootName:
                    rootKey = Registry.CurrentConfig;
                    break;

                default:
                    throw new ArgumentException("Path root is invalid or missing");
            }

            return rootKey;
        }

        /// <summary>
        ///     Return registry key at supplied path. If the key or its parents don't exist, create them before returning.
        ///     The returned RegistryKey is writable.
        /// </summary>
        /// <param name="fullPath">Path of the key to open or create. Not case-sensitive.</param>
        public static RegistryKey CreateSubKeyRecursively(string fullPath)
        {
            if (fullPath == null)
                throw new ArgumentNullException(nameof(fullPath));

            if (fullPath.Length < 4)
                throw new ArgumentException("Path is too short/invalid");

View on GitHub (pinned to 608321de98)

Solutions

1. Spell the root as one of: HKLM, HKCR, HKCU, HKU, HKUS, HKCC, or HKEY_LOCAL_MACHINE, HKEY_CLASSES_ROOT, HKEY_CURRENT_USER, HKEY_USERS, HKEY_CURRENT_CONFIG.
2. Ensure the root is separated from the rest by a single backslash and that nothing precedes it (no leading whitespace, no drive-style prefixes).
3. If you need an unsupported hive (e.g. HKEY_PERFORMANCE_DATA), open it directly via Microsoft.Win32.Registry instead of routing through this helper.
4. Log fullPath.ToUpperInvariant() at the call site to see exactly which token the switch is rejecting.

Example fix

// before
var k = RegistryTools.OpenRegistryKey("HKEY_LOCAL_MASHINE\\Software\\Foo", true);

// after
var k = RegistryTools.OpenRegistryKey("HKEY_LOCAL_MACHINE\\Software\\Foo", true);
// or short form
var k = RegistryTools.OpenRegistryKey("HKLM\\Software\\Foo", true);

private static readonly HashSet<string> ValidRoots = new(StringComparer.OrdinalIgnoreCase)
{
    "HKLM","HKCR","HKCU","HKU","HKUS","HKCC",
    "HKEY_LOCAL_MACHINE","HKEY_CLASSES_ROOT","HKEY_CURRENT_USER","HKEY_USERS","HKEY_CURRENT_CONFIG"
};
private static bool IsRootValid(string fullPath)
{
    if (string.IsNullOrWhiteSpace(fullPath)) return false;
    var seg = fullPath.Split('\\', '/')[0];
    return ValidRoots.Contains(seg);
}

static bool IsLikelyRegistryPath(string s) =>
    !string.IsNullOrWhiteSpace(s)
    && s.Length >= 4
    && (s.StartsWith("HK", StringComparison.OrdinalIgnoreCase)
        || s.StartsWith("HKEY_", StringComparison.OrdinalIgnoreCase));

try { var k = RegistryTools.OpenRegistryKey(path, writable); }
catch (ArgumentException ex) when (ex.Message.Contains("Path root is invalid"))
{ /* log path.ToUpperInvariant() and surface to user */ }

When it happens

Trigger: Calling OpenRegistryKey / CreateSubKeyRecursively / GetRootHive with a path whose first segment is misspelled (e.g. 'HKEY_LOCAL_MASHINE', 'HKLMX'), uses an unsupported hive (HKEY_CURRENT_USER_LOCAL_SETTINGS, HKEY_PERFORMANCE_DATA, HKEY_DYN_DATA), or starts with a relative/empty token before the first backslash.

Common situations: Copy-pasting a registry path from documentation that uses a non-canonical hive name; building paths via string concatenation where the root constant is wrong; paths imported from a .reg file using hive variants the switch does not enumerate; locale-specific typos.

Related errors

• Path cannot be empty or null
• Path cannot point to a root key
• Cannot remove the default value
• Path does not point to a valid .reg file
• Path is too short/invalid

AI-assisted analysis of BCUninstaller/Bulk-Crap-Uninstaller@608321de98 (2026-08-13). Data as JSON: /api/errors/0a022c116045944a. Report an issue: GitHub.