peass-ng/PEASS-ng · warning · DeviceNotReadyException

ERROR_NOT_READY

ERROR_NOT_READY

Error message

({21}) The device is not ready: [{drive}]

What it means

DeviceNotReadyException raised by ExistsDriveOrFolderOrFile when the drive backing the path exists but the OS reports ERROR_NOT_READY (21), i.e. the device has no media or is not initialized. AlphaFS throws this so callers explicitly learn a drive letter exists yet is unusable, rather than getting a false 'not exists' result.

Source

Thrown at winPEAS/winPEASexe/winPEAS/3rdParty/AlphaFS/Filesystem/Directory Class/Directory.ExistsDrive.cs:76


      /// <summary>[AlphaFS] Checks if specified <paramref name="path"/> is a local- or network drive.</summary>
      /// <returns><c>true</c> if the drive exists, <c>false</c> otherwise.</returns>
      internal static bool ExistsDriveOrFolderOrFile(KernelTransaction transaction, string path, bool isFolder, int lastError, bool throwIfDriveNotExists, bool throwIfFolderOrFileNotExists)
      {
         if (Utils.IsNullOrWhiteSpace(path))
            return false;


         var drive = GetDirectoryRootCore(transaction, path, Path.IsPathRooted(path) ? PathFormat.FullPath : PathFormat.RelativePath);

         var driveExists = null != drive && File.ExistsCore(transaction, true, drive, PathFormat.FullPath);

         var regularPath = Path.GetCleanExceptionPath(path);


         if (!driveExists && throwIfDriveNotExists || lastError == Win32Errors.ERROR_NOT_READY)
            throw new DeviceNotReadyException(drive, true);


         throwIfFolderOrFileNotExists = throwIfFolderOrFileNotExists && lastError != Win32Errors.NO_ERROR;

         if (throwIfFolderOrFileNotExists)
         {
            if (lastError != Win32Errors.NO_ERROR)
            {
               if (lastError == Win32Errors.ERROR_PATH_NOT_FOUND)
                  throw new DirectoryNotFoundException(regularPath);


               if (lastError == Win32Errors.ERROR_FILE_NOT_FOUND)
               {
                  if (isFolder)
                     throw new DirectoryNotFoundException(regularPath);

                  throw new FileNotFoundException(regularPath);

View on GitHub (pinned to 53fb989abc)

Solutions

  1. Physically/media-remediate the device: insert media, re-seat or reconnect the drive, restore the network share.
  2. Retry after a short delay for transient unready states (spinning-up USB drives, reconnecting shares).
  3. Wrap the existence check in try/catch for DeviceNotReadyException and treat the drive as 'unavailable' instead of failing the scan.
  4. Filter out known unready letters before probing (e.g. check logical drive type/media via DriveInfo.IsReady).

Example fix

// before
bool exists = Directory.ExistsDrive(driveRoot);
// after
bool exists;
try { exists = Directory.ExistsDrive(driveRoot); }
catch (DeviceNotReadyException) { Log.Warn($"{driveRoot} not ready"); exists = false; }
Defensive patterns

Strategy: try-catch

Validate before calling

var di = new DriveInfo(Path.GetPathRoot(path) ?? "");
if (!di.IsReady) { Log.Warn(drive + " not ready"); return; }

Type guard

static bool IsDriveReady(string path) { var root = Path.GetPathRoot(path); return root != null && new DriveInfo(root).IsReady; }

Try / catch

try { exists = Directory.ExistsDrive(path); } catch (DeviceNotReadyException ex) { Log.Warn($"Device not ready: {ex.Message}"); exists = false; }

Prevention

When it happens

Trigger: Directory.ExistsDrive(path) where File.ExistsCore confirms the drive root exists but lastError == Win32Errors.ERROR_NOT_READY — typically accessing an empty CD/DVD drive, an unmounted/sleeping removable drive, a disconnected network drive, or an offline VHD.

Common situations: Inventory/audit tools (like winPEAS) scanning all drive letters and hitting a card reader slot with no card, a USB stick that was yanked mid-session, or a mapped network drive whose host is unreachable.

Related errors

AI-assisted analysis of peass-ng/PEASS-ng@53fb989abc (2026-09-02). Data as JSON: /api/errors/f5276e9c11ebf770. Report an issue: GitHub.