No, Microsoft hasn’t issued a “Windows 10 update warning”

Fool me once, shame on you. This time the shame’s on me.

I click through on clickbaity things from time to time, and I decided to see if the breathless report from one of the major online publications had picked up something that slipped under my radar.

Nope. I need to rap my own knuckles here.

Here’s the fact. The “optional,  non-security, C/D Week” patch for Win10 version 1903 and 1909, KB 4535996, has a bunch of problems. Mayank Parmar first wrote about them on March 5 in Windows Latest. Lawrence Abrams repeated that list and added a few more the next day in BleepingComputer.

We’re seeing a handful of common installation bugs:

• The patch won’t install, or rolls back
• There are blue screens or black screens after installation
• Complaints of slowness from various sources

We’re also seeing one novel problem, first reported (to the best of my knowledge) by Rafael Rivera. The tool used by Visual Studio to self-sign code, signtool.exe, triggers “Failed to sign” errors after installing the update:

If you’re having trouble with signtool.exe, check if you have KB4535996 (optional 2020-02 CU) installed. Looks like WTLogConfigCiScriptEvent got removed from wldp.dll without sufficient testing.

Microsoft has listened to Rivera (for a change!) and a Visual Studio community post from a Microsoft engineer now says:

We’re aware of issues with signtool.exe after installing the latest optional update for Windows 10, version 1903 or Windows 10, version 1909 (KB4535996). If you are encountering issues or receiving errors related to signtool.exe, you can uninstall the optional update KB4535996. We are working on a resolution and estimate a solution will be available in mid-March.

Of course, neither the Knowledge Base article nor the official Windows Release Information page say squat.

I haven’t talked much about these bugs here because I rarely talk about bugs in beta software — and, make no mistake, the monthly “optional, non-security, C/D Week” patches are beta versions. Maybe even alpha, depending on your definitions. The changes in those patches graduate to full, living, breathing cumulative updates on the following Patch Tuesday.

Neither Susan nor I ever, ever, ever recommend that you install the monthly optional updates. There’s too much downside, and almost no upside. This is a case in point.

This month, though, things are a little different. With nearly all of Microsoft’s employees now working from home, it isn’t clear if all the known bugs (much less the unknown ones!) will get fixed in time for Tuesday. But I’ll have more about that tomorrow in Computerworld.