Microsoft releases some 'optional, non-security, C/D Week' Win10 patches. Avoid them.

In a return to its boorish behavior, Microsoft released several Windows 10 patches, presumably to preview non-security fixes as well as another .NET preview. Microsoft had stopped releasing these confusing middle-of-the-month patches in March, citing “the public health situation.” The patches are back anyway.

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I’ve always detested Microsoft’s “optional, non-security, C/D Week” patches because they’re confusing, easy to install accidentally, rarely solve any pressing problems, and potentially introduce yet more bugs. 

Guess what? They’re back. 

As promised last month, Microsoft has started pushing them out again.

In a twist, they’re only being offered via Windows Update (or for manual download). That means organizations using update servers need to jump through several hoops to get them distributed. Few will bother. That’s OK. These C/D Week patches aren’t meant for stable corporate machines. They’re for enthusiasts and seekers, as well as unsuspecting normal users who get sucked in as beta testers.

Perhaps the cruelest irony: Microsoft stopped releasing these patches back in March for a good cause, saying at the time:

We have been evaluating the public health situation, and we understand this is impacting our customers. In response to these challenges we are prioritizing our focus on security updates. Starting in May 2020, we are pausing all optional non-security releases (C and D updates) for all supported versions of Windows client and server products (Windows 10, version 1909 down through Windows Server 2008 SP2).

There is no change to the monthly security updates (B release – Update Tuesday); these will continue as planned to ensure business continuity and to keep our customers protected and productive.

Now it appears that Microsoft has re-evaluated the public health situation and, in light of our great strides in defeating the pandemic, determined that the old ways should return.

As of July 20 and 21, we have 33 new patches in the Microsoft Update Catalog.  They include:

  • KB 4559004 – the 2020-07 Cumulative Update Preview for Win10 versions 1909, 1903; and KB 459003 for 1809 and Server 2019.
  • KB 4562900 – the Cumulative Update Preview for .NET Framework 3.5 and 4.8 for Win10 versions 1903 and 1909; and a handful of similar previews for other versions of .NET, Windows and Server.

All of those patches should appear in Windows Update (Start > Settings > Update & Security) as separate entries with Download and Install links. In theory, you won’t get the offered Preview patch installed unless you click Download and install.

In my tests, though, clicking to Resume Updates on a Win10 1909 system installed the .NET patch. I did not click Download and install. The Preview just installed itself.

As of very early Wednesday morning, I don’t see the Cumulative Update Preview offered on any of my Win10 1909 machines. They don’t appear while running wushowhide, either. Maybe I’m just lucky.

Of course you should avoid these patches. They’re still in testing; that’s why they’re marked “Preview.” But more to the point, you should be asking why Microsoft decided that the “public health situation” now warrants foisting more error-prone garbage down our throats. 

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