Windows 7: Issues with Update KB890830 (MSRT) confirmed

[German]A brief addendum for users of Windows 7 SP1 and Windows Server 2008/R2, who had trouble with update KB890830 (MSRT) in November. Microsoft has indirectly admitted that they pulled KB890830 from Windows Update due to issues.

What was the MSRT problem?

Update KB890830 is the 'Windows Malicious Software Removal Tool' (MSRT). The tool is available for all versions of Windows and is rolled out cyclically on patchday as an update to clean the systems from malicious software (certain common threats such as Trickbot).

The update was also rolled out on Patchday (November 12, 2019) for all Windows versions via Windows Update. But this MSRT version from November 12, 2019 causes issues in Windows 7 SP1 and Windows Server 2008/R2. Already on Patchday there were comments like this:

With KB890830 all my installation attempts fail.
Error Code 0x800B0109

I have also read reports that the tool is being installed again and again. In the blog post Windows 7: Update KB890830 (MSRT) drops Error 0x800B0109 I outlined the background for error 0x800B0109. The error code stands for CERT_E_UNTRUSTEDROOT, which means that the certificate chain was processed though. However, the check ended with a root certificate that is not trusted by the trust provider.

So, while the KB890830 Update Certificate was invalid for Windows 7 SP1, all other versions of Windows accepted the MSRT Certificate. What caused this problem could not be clarified – probably Windows 7 SP1 lacks a corresponding root certificate.

MSRT reissued and pulled from Windows Update

Shortly after the patchday blog readers reported that the update KB890830 was no longer offered via Windows Update. In the blog post Windows 7: Update KB890830 (MSRT) drops Error 0x800B0109 I had pointed out that an updated version of the MSRT (update KB890830) for Windows 7, Windows Server 2008 and Windows Server 2008 R2 (dated 11/13/2019) has been released in Microsoft Update Catalog. So Microsoft has changed something. I also reported that I was able to download the MSRT from the Update Catalog and run it successfully on Windows 7.

Now a blog reader has pointed out an addition in the support post for KB890830 . Microsoft has added the following passage:

Due to certificate chain verification issues on pre-Win10, the MSRT package of November 2019 will not be offered via Windows Update.

Please download the package from Download site to run on these platforms.

Microsoft therefore no longer offers the MSRT for all Windows versions prior to Windows 10 for November 2019 via Windows Update. The reason is a problem in the certificate chain. The recommendation is to download the tool manually and then run it for verification. So exactly what I had already outlined in the blog post Windows 7: Update KB890830 (MSRT) drops Error 0x800B0109.