Microsoft has released the optional cumulative update KB5006738 Preview for Windows 10 2004, Windows 10 20H2, and Windows 10 21H1.
Microsoft claims that this update and a separate Windows Server Preview update will resolve any outstanding printing issues affecting users as it has mitigated the vulnerabilities of PrintNightmare.
Cumulative update KB5006738 is part of Microsoft’s September 2021 “C” monthly update, allowing Windows users to test upcoming fixes before they are released as part of the upcoming Patch Tuesday in November 2021.
Unlike Patch Tuesday updates, “C” preview updates are optional and do not include any security updates.
Windows users can install this update by going to Settings, clicking on Windows Update, and manually performing a ‘Check for updates. ‘
As this is an optional update, you will be asked if you want to install it by clicking on the “Download and Install” link as shown in the image below.

Windows 10 users can also manually download and install the KB5006738 preview update from the Microsoft Update Catalog.
Corrections released for many printing issues
With the release of Windows 10 update KB5006670, users started to experience many issues printing or installing new printers.
With today’s update, Microsoft claims to have fixed an issue that prevents the installation of printers through Internet Printing Protocol (IPP).
Microsoft also claims to have fixed the following printing issues with a separate Windows Server Preview Update KB5006745 released today:
- Addresses a known issue that prevents an Internet print server from properly packaging changed printer properties before sending the package to the client.
- Addresses a known issue that could prevent the successful installation of printers using Internet Printing Protocol (IPP).
- Addresses a known issue that may ask for administrative credentials every time you try to print. This occurs in environments where the print server and print client are in different time zones.
What’s new in Windows 10 KB5006738
After installing this update, Windows 10 2004 will be updated to Build 19041.1320, Windows 10 20H2 will be updated to Build 19042.1320, and Windows 10 21H1 will be updated to Build 19043.1320.
Windows 10 Cumulative Update Preview KB5006738 includes twenty improvements or fixes, the highlighted ones are listed below:
- Addresses an issue that could prevent the display of closed captions for some video applications and video streaming sites.
- Addresses an issue that prevents Windows 10 Virtual Private Network (VPN) users from connecting to Windows Server 2019 Routing and Remote Access Service (RRAS) servers.
- Addresses an issue that causes Windows to enter BitLocker recovery after a maintenance update.
- Addresses an issue that could prevent Kerberos.dll from functioning in the Local Security Authority Subsystem (LSASS) service.
- Addresses a code integrity issue that could cause a memory leak.
A complete list of fixes is available in Support Bulletin KB5006738.