If Printix printing and IPP printing has stopped working (see symptoms below) it is caused by an issue in Windows Defender version 4.18.2001.10 and its MpPrintFlt.dll file.
As an alternative to the below workaround you can download and run the PowerShell script:
Remember to rename the file so it is without the .txt extension.
- Check the version of the MpPrintFlt.dll file installed in the C:\Windows\System32 folder. Open a command prompt (CMD) and type:
wmic datafile where name="C:\\Windows\\System32\\MpPrintFlt.dll" get Version /value
Alternatively, right-click the file and select Properties, and then select the Details tab to see the File version.
- Check that the version of Windows Defender on the computer has been updated to version 4.18.2003.6 or later. Browse to:
The name of the subfolder reflects the version, for example:
If the version is not 4.18.2003.6 or later, then use Windows Update to get the latest version.
- Stop the Print Spooler on the computer.
Select Windows logo key + R to open Run. Type: services.msc, and select OK. Right-click Spooler. Select Stop.
Alternatively open a command prompt (CMD), as administrator (Right-click and select Run as administrator). Type: net stop spooler
- Delete file C:\Windows\System32\MpPrintFlt.dll
- Copy the latest MpPrintFlt.dll from the Platform subfolder, Example:
- Start the Print Spooler on the computer.
Select Windows logo key + R to open Run. Type: services.msc, and select OK. Right-click Spooler. Select Start.
Alternatively open a command prompt (CMD), as administrator (Right-click and select Run as administrator). Type: net start spooler
- Printing via printers that are setup to use IPP (Internet Printing Port), including Printix printers, has stopped working.
- These printers appears with Status Unavailable.
- The Print button may appear dimmed.
- When opening the Printer properties dialog, you get dialog with:
The handle is invalid.
How does this look in Windows registry?
- Select Windows logo key + R to open Run.
- Type: regedit, and select OK.
- In Registry Editor browse to:
ControlSet001\Control\Print\Providers\Internet Print Provider
- Check that value of Name.
Computer with this issue:
- On a computer with the above issues the Name has the value: MpPrintFlt.dll
Computer without this issue:
- On a normal computer the Name has the value: inetpp.dll