BCUninstaller/Bulk-Crap-Uninstaller · error · IOException

Win32_Directory.Compress returned {ret}

Error message

Win32_Directory.Compress returned {ret}

What it means

Thrown by FilesystemTools.CompressDirectory after invoking the WMI method Win32_Directory.Compress. It casts outParams.Properties["ReturnValue"].Value to uint and, if it is non-zero, throws IOException with the code appended. Non-zero return codes from this WMI method indicate failure (e.g. access denied, path not found, the directory is on a volume that does not support NTFS compression).

Source

Thrown at source/KlocTools/Tools/FilesystemTools.cs:125

                Directory.Move(source.FullName, target.FullName);
            else
            {
                CopyRecursive(source, target);
                source.Delete(true);
            }
        }

        public static void CompressDirectory(string dirFullName) => CompressDirectory(dirFullName, ManagementOptions.InfiniteTimeout);
        public static void CompressDirectory(string dirFullName, TimeSpan timeout)
        {
            var objPath = "Win32_Directory.Name=" + "\"" + dirFullName.Replace(@"\", @"\\") + "\"";
            using (var dir = new ManagementObject(objPath))
            {
                var outParams = dir.InvokeMethod("Compress", null, new InvokeMethodOptions { Timeout = timeout });
                if (outParams == null) throw new ArgumentNullException(nameof(outParams));
                var ret = (uint)outParams.Properties["ReturnValue"].Value;
                if (ret != 0)
                    throw new IOException("Win32_Directory.Compress returned " + ret);
            }
        }

        [DllImport("shlwapi.dll")]
        public static extern bool PathIsNetworkPath(string pszPath);

        [DllImport("kernel32.dll", EntryPoint = "CreateSymbolicLinkW", CharSet = CharSet.Unicode)]
        private static extern int CreateSymbolicLink([In] string lpSymlinkFileName, [In] string lpTargetFileName,
            SymbolicLinkType dwFlags);
    }
}

View on GitHub (pinned to 608321de98)

Solutions

1. Ensure the target volume is NTFS (or ReFS where supported) before compressing.
2. Run the host process elevated and confirm WMI service (winmgmt) is healthy.
3. Decode the ReturnValue (e.g. 2 = access denied, 3 = path not found) and surface a meaningful error; fall back to the Win32 DeviceIoControl FSCTL_SET_COMPRESSION P/Invoke if WMI is unreliable.

Example fix

// before
FilesystemTools.CompressDirectory(@"E:\MyDir"); // E: is FAT32 -> code 11

// after: guard against non-NTFS and report the code
if (new DriveInfo(Path.GetPathRoot(dir)).DriveFormat != "NTFS")
    throw new InvalidOperationException("Compression requires an NTFS volume.");
try { FilesystemTools.CompressDirectory(dir); }
catch (IOException ex) { logger.Error($"Compress failed: {ex.Message}"); }

var root = Path.GetPathRoot(dirFullName);
if (new DriveInfo(root).DriveFormat != "NTFS") return; // skip non-NTFS
FilesystemTools.CompressDirectory(dirFullName);

try { FilesystemTools.CompressDirectory(dir); }
catch (IOException ex) { logger.Warn($"Compress failed ({ex.Message}). Code may indicate access/path/FS error."); }

When it happens

Trigger: Calling CompressDirectory on a path that does not exist, is on a non-NTFS volume (FAT32/exFAT), when the process lacks SeManageVolumePrivilege / admin rights, or when WMI is broken/disabled.

Common situations: Portable apps run from FAT32 USB drives, non-elevated processes, WMI repository corruption, or paths with characters that break the WMI object path escaping.

Related errors

• Not a Windows .exe file.
• Path does not point to a valid .reg file
• Process name can't be null or empty
• Path is too short/invalid
• Minimum value must be lower than or equal to the maximum val

AI-assisted analysis of BCUninstaller/Bulk-Crap-Uninstaller@608321de98 (2026-08-13). Data as JSON: /api/errors/aed3f43922de6a82. Report an issue: GitHub.