What we know about KB 3150513

UPDATE: More info in this InfoWorld Woody on Windows.

On March 15, the Thursday after Patch Tuesday, Microsoft re-re-released KB 3150513. It’s innocuously titled “Latest compatibility definition update for Windows,” but it’s raised a lot of suspicion for those of us who prefer our Windows snooping overt, not covert.

Microsoft’s description:

This update provides the latest set of definitions for compatibility diagnostics that are performed on the system. The updated definitions will help enable Microsoft and its partners to ensure compatibility for all customers who want to install the latest Windows operating system. Installing this update also makes sure that the latest Windows operating system version is correctly offered through Windows Update, based on compatibility results.

Which is enough to get my tinfoil hat twitching.

We had a similar not-quite-documented appearance of KB 3150513 back in September.

Here’s what we know for sure:

The update includes files called Appraiser.sdb and Appraiser_telemetryrunlist.xml.

It was offered on just about every version of Windows you can name. The KB article lists prerequisites, but there are versions for Win10 1607, 1511, Windows 8 (!) and 8.1, and Win 7 RTM (!) and SP1. In addition @ch100 documents that a version is also available for Windows Server 2016, for the first time.

When it appeared in September, poster K hid it, but it re-appeared two additional times. At the time, I documented that it appeared twice, with two different dates, May 4 and May 11, 2016.

In September, @abbodi86 viewed it as a precursor to upgrading to the Win10 Anniversary Update (released July 2016):

it’s an update for the system’s compatibility database, which is related the famous schedule task “Microsoft Compatibility Appraiser”. This diagnostics is required to see if the current machine is applicable for RS1 upgrade through WU. Yes, it may involves sending “telemetry” feedback but isn’t whole Windows 10 is already telemetry-connected?

With regard to the March 15 release, @PKCano says:

This is being offered on all versions of Windows. It is a compatibility definition update. A new release for Win10, but Win7 and Win8.1 are seeing the earlier version appear if they installed KB2952664 (Win7) or KB2976978 (Win8.1) with the recent updates. The latter are prerequisites. It is also showing up in Win10.

And @abbodi86 says

Appraiser KB2952664 and Telemetry DiagTrack are built-in Windows 10 since RTM. Both KB2952664/KB3150513 are only needed for upgrade they have nothing useful for current Windows 7 (well, except providing MSFT with Appraiser statistics)

And @ch100:

Other versions were released in the past for Windows 10 1511.
To me, without having the full details, it indicates that the functionality from KB2952664 in Windows 7 is built-in at least in Windows 10 1511 and 1607. Otherwise we wouldn’t see KB3150513 being on offer for those versions of Windows 10.
There was no KB3150513 release for Windows 10 1507.

Does anybody else have some definitive information on this beast? Is there any reason at all to install it, unless you plan on upgrading to the Win10 Creators Update version as soon as it’s available (which is an incredibly poor choice, but more about that later)?