How to fix Error 36 on Windows 11

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Troubleshooting Guide: Error 36 – “Too Many Files Opened for Sharing” (Windows 11)

Why This Error Happens

Error 36 occurs when the SMB (Server Message Block) file sharing service exceeds the maximum number of concurrently open file handles allowed by the system’s registry configuration. This typically happens on systems with default consumer-grade sharing limits that are set too low for the actual network load, especially when multiple users or applications access shared folders simultaneously. It can also be triggered by a misconfigured MaxWorkItems or MaxMpxCt registry value, or by an unusually high number of small files being accessed at once through a single share.

Step-by-Step Resolution Guide

  1. Open the Registry Editor
    Press Win + R, type regedit, and press Enter. Navigate to:
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters

  2. Increase the MaxMpxCt value
    Look for a DWORD value named MaxMpxCt. If it doesn’t exist, right-click the Parameters folder → New → DWORD (32-bit) Value, name it MaxMpxCt, and set its value (in Decimal) to 500 or higher (default is often 50).

  3. Adjust MaxWorkItems (if present)
    In the same key, check for MaxWorkItems. Set this to 65535 (Decimal) to allow more simultaneous work requests to be processed by the server service.

  4. Increase the Irpstacksize
    Navigate to:
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters
    Add or modify a DWORD value named IRPStackSize and set it to 20 (Decimal) — this allocates more memory for I/O request packets, which is often the direct cause of “too many files open” errors.

  5. Restart the Server Service
    Open Command Prompt as Administrator and run:

   net stop server
   net start server

Alternatively, restart the machine to ensure the registry changes take full effect.

Alternative or Verification Steps

  • Verify the fix: Re-access the shared folder from multiple client machines simultaneously and check Event Viewer (Windows Logs > System) to confirm Error 36 no longer appears under the source Srv.
  • Alternative fix: If the error persists, reduce the number of files being shared per folder by splitting large directories into multiple smaller shares, or upgrade to Windows Server for higher built-in SMB connection limits.