KB5001391 is another Windows update that you should not install, except..

Martin Brinkmann
May 3, 2021
Updated • May 3, 2021
Windows, Windows 10

Microsoft released the Windows update KB5001391 on April 28, 2021 as an optional update for Windows 10 version 2004 and 20H2. The update falls into the C-category of updates for Windows, which means that it includes only non-security fixes and that installation is not mandatory.

In fact, Windows Update will display the update when it is opened but it is up to the administrator of the system to start the installation of the patch manually.

The update fixes a number of issues, including a memory usage growth issue in lsass.exe that causes the system to become unusable, a high CPU usage issue caused by race conditions, and an issue with a deadlock in NTFS.

It is also the update that introduces Microsoft's News and Interests widget on the Windows 10 taskbar. The feature is being rolled out gradually to all devices that have the update installed.

Why you should not install KB5001391 or any other optional update

kb5001391 cumulative update windows 10

KB5001391 is an optional update. Microsoft releases these to collect Telemetry data to discover issues before the update is released on the second Tuesday of the following month.

While organizations and administrators may use the update for testing, it is generally not a good idea to install the update on production machines.

Preview updates should be considered beta, which means that they may introduce new issues on machines running Windows 10.

Preview updates caused all kinds of issues on devices in the past, from bluescreen errors and crashes to performance issues.

Microsoft lists known issues on the support page of the update. For KB5001391, three issues are listed that are all long-standing.

Final update releases, e.g. those on the second Tuesday of a month, may also introduce issues, but Microsoft is fixing issues in updates released for preview before these updates are released as final versions for all devices running Windows 10.

Reasons for installing optional updates

Optional updates should not be installed on most Windows 10 devices. There are legitimate reasons for installing these updates:

  • For testing purposes -- The optional updates give system administrators about two weeks to run tests before the final version of these updates are released. It is helpful, as it enables administrators to make sure that the update installs and runs fine on systems, or to spot issues quickly to prevent the installation of updates until the issues are fixed-
  • For fixing purposes -- All optional updates include fixes for issues that users may experience when they work on Windows 10 devices. Bugs that affect users critically may be fixed by these updates, and it is often a good idea to install these to resolve the issues about two weeks before the final update release.

Closing Words

Optional updates provide a preview of the fixes that will be introduced on the coming Patch Tuesday, this makes them ideal for testing purposes and quick fixes for critical issues. The majority of users should ignore preview updates because of their beta status and the potential for introducing unmentioned issues on Windows 10 devices.

Now You: do you install optional Windows updates?

KB5001391 is another Windows update that you should not install, except..
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KB5001391 is another Windows update that you should not install, except..
Find out why you should not install optional updates for Windows devices that Microsoft releases, and reasons for installing them.
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  1. NutDriver said on May 9, 2021 at 7:00 pm

    I removed KB5001391 optional update after experiencing exceptionally long boot times. The slow boot went away when removing this update. Don’t fix it if it ain’t broke my dad used to say….

    Hopefully when the full release is force-fed, it won’t cause the slow boots.

  2. Sanles said on May 8, 2021 at 11:02 pm

    I’ve got a perpetual copy of Microsoft Office 16 and it started glitching and not responding directly after the install. It got to the point where it was frustrating to use it. I didn’t have the update installed long enough to know if other areas were affected. Once I uninstalled KB5001391 the program became smoother and better behaved.

  3. Jim Vanderbilt said on May 8, 2021 at 5:12 pm

    I was under the impression that preview updates were already-finalized parts of the monthly updates, with the only purpose to reduce the peak on MS Tuesday. So I installed them always, will of course stop doing so after this article.

    1. Bret said on May 8, 2021 at 10:32 pm

      Same here Jim. I was going to reboot my computer and thought, “wonder if there are any pending updates” so I could save myself from a forced reboot in the future. I didn’t “jump to install” it as suggested above.

  4. Anonymous said on May 6, 2021 at 6:37 am

    Microsoft should test their updates making sure they WORK! I’ve had to revert 8 times, back to an older version of Window’s because every time I’ve updated to Window’s 10 in won’t recognize WiFi. Trying to contact support to talk to an living person is a joke and even more of a joke “if” they try and fix whatever problem the customer is having. Screw Microsoft!

    1. Jack said on May 6, 2021 at 12:34 pm

      There’s obviously a limit to how much they can test in their labs. Just wait for the final release to be installed automatically, which should hopefully be a smoother process for you a month or so down the line, or ditch Windows if you can’t tolerate it instead of complaining on random sites.

  5. Bret said on May 6, 2021 at 12:28 am

    I found this page because I had a horrible experience with the KB5001391 update. The system process immediately pegged at 100% disk use and I should have immediately rolled it back but instead tried a dozen things to reduce the load. No joy. Rolled back. Computer is happy again. I will not be experimenting any more.

    1. Jack said on May 6, 2021 at 12:32 pm

      Wait for the final release instead of jumping to install optional/preview updates, unless they specifically claim to fix some severe issue you’re facing.

  6. Janne Granström said on May 5, 2021 at 1:11 am

    when Kyocera happens, microsoft released a preview update to fix that issue, i have no other choice than install it.

  7. beemeup5 said on May 4, 2021 at 1:18 pm

    I’ve been literally running Windows 7 SP1 without any updates for almost exactly 10 years now. Completely problem free! I manually installed one patch to enable PCI-Express NVME booting and that was it.

    An operating system exists to run your applications. The applications can be updated every now and then but the operating system itself needn’t be touched.

    Enterprise environments are different. If you can’t keep it secure, don’t use Windows XP etc.

    1. Anon said on May 4, 2021 at 10:30 pm

      Hopefully you are knowledgeable enough to keep your system secure, and not bother the rest of us by being part of some bloody botnet. Unfortunately, 99.9999…% of people who stubbornly cling on to XP, Win7 etc. on internet-connected PCs and consider themselves as amazing OS and security experts are only full of hot gaseous matter.

      1. Run said on May 5, 2021 at 12:30 am

        I rather be a botnet than being Microsoft’s guinea pig for botched updates. News and Interests widget is solid evidence that inexperienced kids are working on Windows shell. There is no thought and common sense put into any of these new features. Where are all the adults at Microsoft?

        News and Interests widget text is extremely blurry. The icons are jagged and jarring. If your taskbar is positioned anywhere but the bottom of your monitor, the options to disable this vanish, and sometimes so does the weather bar itself. CPU usage spikes when scrolling through the content, and it’s laggy and jumpy. If you have text size set to anything over 100%, it breaks the column display in the widget. These are all things I noticed within 5 minutes of it installing itself on my computer.

      2. Anon said on May 5, 2021 at 1:29 pm

        All valid concerns about this feature if true, @Run, and absolutely reason enough for Microsoft to either improve this ASAP or make it optional or get rid of it altogether. None of this however is sufficient reason IMO to stick with a 12 year old (Win7) or worse 2 decade old OS (XP). My policy towards those who don’t like Win10’s UI is to either suggest they install something like Classic Shell (which most such people prefer, plus they continue to profit from a decade+ worth of improvements in Windows hardware support and security), or tell them to make the effort and switch to Linux. Especially on aging hardware, that is a *far* better option than stubbornly and stupidly clinging to unsupported XP or Win7. Better for them, and doubly better for the rest of us, since we’re not subjected to their stupidity and ignorance either.

  8. Scientific Frontline said on May 4, 2021 at 12:20 pm

    Only live once, of course I install them. Though I also run a full O&O Image back-up before installing the sure to fail MS updates. 😁
    Though no issues with KB5001391, yet would make changes to the way “News and Interest” works.

  9. Hăkio said on May 4, 2021 at 7:52 am

    I always check for update and installing the latest version as possible, because for me and my device configuration, Windows update always (99%) improving the existed experience, and (1%) causing trouble, also, Windows update is now fast as FKXK

  10. Zelanium said on May 4, 2021 at 7:37 am

    The fact that this has the awful news and interests widget is reason enough to block it. This is the ultimate, final insult to Windows users; adware constantly pinging servers, eating bandwidth and RAM, and the whole point is directing traffic to Microsoft’s friends in the media. You can configure it? Most people never will, instead getting trashy tabloid news in their taskbar, together with the current weather which I’m able to figure out by looking out of the window.

    1. Germanium said on May 4, 2021 at 10:21 pm

      If most people can’t be bothered to block or even configure this, just how is it “the ultimate, final insult” to them? Clearly they don’t care enough and will continue as usual.

      1. owl said on May 5, 2021 at 9:53 am

        > Clearly they don’t care enough and will continue as usual.

        Microsoft has restructured (abolished) “QA (Quality Assurance) teams” that cost a lot of money (property and labor costs for, various testing equipment, number of persons, work efficiency, securing the work environment, etc.) in all product and project departments, replaced with “AI”.
        Microsoft and Google are thoroughly implementing “profit first” from the perspective of shareholder measures, and are aggressively moving “from people to AI” in order to reduce costs.
        The “HOME” version, which is commonly used for home user applications, is a “low-priced product” that has been mass-produced, so users have a limited degree of freedom in personalization, and it is difficult to avoid becoming a beta user.

      2. Germanium said on May 5, 2021 at 1:15 pm


        Nothing you’ve stated is new (Microsoft reduces QA) or not obvious (Apple, Amazon, Google, Microsoft et al want to maximize profit – le gasp!), and neither point is relevant here. Even Home users can turn off display of this feature (though of course I’d have preferred a way to uninstall it completely) or customize it. As Zelanium rightly said, most will do neither, so that in itself is proof that they won’t consider this “the ultimate, final insult” to them, since they’ll just not care and will continue as usual.

    2. owl said on May 4, 2021 at 9:37 am


      Absolutely right,
      I agree with your view in its entirety.

  11. Harro Glööckler said on May 4, 2021 at 4:25 am

    > The majority of users should ignore preview updates because of their beta status and the potential for introducing unmentioned issues on Windows 10 devices.
    If the majority does that, then it will just introduce more issues. Bugs don’t exist if nobody reports them.

    I always install all preview/rc updates for all software and never had any problems since most of them are like “you get it on Friday while everyone else gets it on Monday”. The only updates that gave me headaches are nightlies and alphas, but those aren’t meant for daily usage anyways.

    1. Zelanium said on May 4, 2021 at 7:52 am

      You have had issues, you just didn’t realize it. Last year, Windows had a bug for several months which affected the disk optimizer and caused it to needlessly defrag SSD drives (bad); it also had a bug that broke the way files are opened from saved searches (made the OS unuseable for me), that bug was fixed in January (introduced last summer). I have also seen it on earlier Windows 10 versions. That was all in the stable, non-preview branch.

      You completely ignore the fact that Windows is a commercial OS by a multi-billion $ corporation for which people pay; it’s used by companies and people who want to trust their OS and professional support. It’s not a community-driven effort of bug-hunting and bluescreen watching. The article is completely correct.

      1. owl said on May 4, 2021 at 9:37 am


        Absolutely right,
        I agree with your view in its entirety.

  12. No Ten said on May 4, 2021 at 2:13 am

    Windows 10 is so FUBAR.

    Linux, BSD, macOS, Windows 7, and Windows 8.1 are the only viable modern desktop operating systems. Windows 10 is garbage and needs to be scrapped.

    1. Bateau said on May 4, 2021 at 3:00 pm

      Linux? With 2% market share on desktop and dozens of distros to create fragmentation and user confusion? Surely you jest.

      Chrome OS (based on Gentoo) is more successful in the desktop market than ALL Linux distros combined and it only took it 4 years to get there.

  13. Anonymous said on May 4, 2021 at 12:52 am

    News and Interests should be in the store, not baked into the OS. The team behind this useless feature should be fired.

    1. Anon said on May 4, 2021 at 10:13 pm

      It’s not something that belongs in the Store, but it absolutely should be part of the Optional Features section under Settings.

      But let’s see if telemetry tells them how many of the total user base disables this…

    2. Xahid said on May 4, 2021 at 8:15 am

      Absolutely right,
      Why the heck, they don’t have this common sense?

  14. John G. said on May 3, 2021 at 8:44 pm

    570 Mb of cumulative things… and it’s a preview only. Just before 21H1, of course, to be serious. :[

    1. Harro Glööckler said on May 4, 2021 at 7:54 am

      570mb? Seems like you’re missing many prior updates. In my case it was something like 10mb and the install (+ reboot) was faster than a typical Windows Defender definitions update.

      1. John G. said on May 4, 2021 at 3:24 pm

        I meant the original file size at Windows catalog, just click the link and so forth. :[

      2. Anonymous said on May 4, 2021 at 10:09 pm

        Yeah John, that’s the way it always is, ‘cos FYI Win10 updates are cumulative.

  15. VioletMoon said on May 3, 2021 at 5:42 pm

    After reading the article posted on BetaNews written by Mark Sofia Wyciślik-Wilson two days ago, I happily and with faith/trust in his advice and reports by other users installed the update:

    “Feedback about the update shows that people who have installed KB5001391 are happy not only with the fact that it adds News and Interests to the taskbar, but also that it seems to be stable and problem free. Some users are even finding that their system is performing better after installing this particular update.”

    I experienced the same, problem-free, better performing computer with the update.

    Your comment, “The majority of users should ignore preview updates because of their beta status and the potential for introducing unmentioned issues on Windows 10 devices” is a radical departure from the inadvertent sense of urgency found in Patch Tuesday gHacks’ articles that stress the importance of updating immediately–preview or otherwise.

    As a general rule, I ignore all Windows 10 updates–on pause–because of the numerous problems that follow installation.

    Medina Spirit!

    1. Martin Brinkmann said on May 3, 2021 at 6:52 pm

      I don’t think that it is a good idea to install previews, unless it is for testing or for fixing major issues. Patch Tuesday updates on the other hand fix security issues, and they are final releases, not considered preview.

      1. Anonymous said on May 7, 2021 at 8:45 pm

        Sometimes (more often than it should happen) those same patches tend to break things. Or worse, crash the OS. This is why my rule of thumb is wait 5 days then roll them out.

  16. blue herring said on May 3, 2021 at 5:02 pm

    I usually do install optional updates, with no problems (that I know of hehe) but when I tried this 1391 one yesterday it failed to install. Good to read your evaluation of it. Now I won’t bother with it— or maybe any other optional ones from now on.

  17. Valrobex said on May 3, 2021 at 3:47 pm

    I don’t install updates to Win 10 because I don’t use it but I know that Tom Hawack does.

    Tom is Micro$oft’s point man for all things Win 10. He is a loyalist when it comes to Win 10 and always installs any and all updates.

    1. What said on May 5, 2021 at 1:13 pm

      “Tom Hawack said on May 4, 2021 at 3:40 pm
      I’m on Windows 7 —”

      You can’t speak for himself. What is Micro$oft or Win? Do you mean Microsoft or Windows?

    2. Kronos said on May 5, 2021 at 1:05 pm

      I do not know who Tom Hawack is, but he must be someone famous given that he has a stalker here! Good on ya Valrobex for being such a Tom Hawack loyalist.

  18. Rixster said on May 3, 2021 at 2:33 pm

    Everybody is now a beta tester, insider, for Microsoft?

    1. Anonymous said on May 4, 2021 at 10:02 pm

      Yes, if they choose to be.

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