Error Message: "Print Processor Is Unknown"


When you attempt to print or connect to a print queue, the following error message may appear:

Could not connect to the printer <printer> because the print processor is unknown.

In addition, printer icons may be missing from the Printers folder.


This error message may be caused by one of the following:

  • The default print processor Winprint.dll is missing on the computer. This file should be located in the following directory:

    %Systemroot%\System32\Spool\Prtprocs\W32x86 -or-
  • The winprint key is corrupted or missing or the data value contains a leading space in the following registry location:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\ Environments\Windows NT x86\Print Processors\

    NOTE: The above registry key is one path; it has been wrapped for readability.


If the Winprint.dll file is missing, expand Winprint.dl_ from the Windows NT installation CD to the %Systemroot%\System32\Spool\Prtprocs\W32x86 directory.

If the winprint key is missing from the registry. you must use Registry Editor to add it. Use the steps below to add the winprint key to the registry:

WARNING: Using Registry Editor incorrectly can cause serious, system-wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk.

  1. Run Regedt32.exe
  2. Navigate to the following registry location:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print \Environments\Windows NT x86\Print Processors\
  3. Click to select the Print Processors key.
  4. On the Edit menu, click Add Key, and then type "winprint" (without the quotation marks) in the Key Name field of the Add Key dialog box (leave the Class field blank).
  5. Click to select the winprint key. On the Edit menu, click Add Value.
  6. Type the following values in the Add Value dialog box and then click OK:

    Value Name: Driver
    Data Type: REG_SZ
  7. For the String Value, type "winprint.dll" (without the quotation marks), and click OK.
  8. Restart the computer. After the computer restarts, you should be able to add printers.

Article ID: 153355 - Last Review: Feb 20, 2007 - Revision: 1