Updates Windows 10

KB3156421 & KB3156387: May Cumulative Updates For Windows 10 [Download]

It has been quite a while since we have had the last Patch Tuesday. Some people were happy about this development, while others speculate that the delay could be to bring us closer to the much anticipated Redstone update. In any case, today Microsoft has released KB3156421 and KB3156387 – the Windows 10 cumulative updates for the month of May. More details after the jump.


It has been some time now since we have last seen any update regarding the row of cumulative updates that used to be routine on Windows 10. Almost midway through May now, and we are seeing the first cumulative update in almost a month. We were honestly expecting this last Tuesday, but better late than never, right?

Anyhow, cumulative update KB3156421 is targeted at users who downloaded the Threshold update back in November. It pushes the build number of Windows 10 10586.318.

The second cumulative update is KB3156387 which is for users on the original release of Windows 10 back in July 2015. It pushes the build number to 10240.16854.

Both build numbers are nice bump over previous builds – April’s cumulative update which were KB3147458 & KB3147461 had the OS build numbers 10586.218 and 10240.16769, respectively.

What’s new in KB3156421 & KB3156387? [Changelog]

KB3156421 update for Windows 10

Below are the highlights of both updates. We be sure to update the changelog as we find more features, if any:

  • General reliability improvements in Cortana, Microsoft Edge, Internet Explorer, Miracast, USB, and Bluetooth.
  • Security improvements and updates throughout the system including Windows Shell, Journal, Microsoft Graphics Component, Internet Explorer 11, and Microsoft Edge
  • Fixed: An issue that caused Bluetooth to work improperly after PC resumed from sleep.
  • Fixed: users would be locked out of their accounts if they failed to sign-in too many times.
  • Fixed: unspecified bug related to daylight savings time.
  • Fixed: unspecified bug that would drain the battery when screen is off.
  • Rumored update i.e. not yet confirmed: FreeSync, G-Sync support as well as support for unlimited framerates in games made on top of the UWP platform.

You can see that the latest update is definitely something that might warrant an install, though if you had a bad history with prior updates, we recommend making a restore point before you proceed.

Downloads for KB3156421 & KB3156387

If you’re unfamiliar with downloading cumulative updates, fret not! We’ll tell you how.

If you’re a novice user, please just wait for Windows 10 to install it automatically for you. While these are good security and reliability updates to have, you don’t need to go out of your way to get them.

You may speed things up by a bit by manually checking for the KB3156421 & KB3156387 updates and pushing Windows 10 to download them. You can do this by launching the Settings app, going into Update & Security and then into Windows Update. From here, you can click on “Check for updates” to do just that.

Of course, if you’re a more advanced user who doesn’t like waiting around, you can always manually download the updates from Microsoft Support. Here they are:

Download KB3156421 for Windows 10 (10586.318) [Microsoft Support]

Download KB3156387 for Windows 10 (10240.16854) [Microsoft Support]

Note: These MS Support links haven’t gone live yet, but we’re familiar with the URL structure, so we’ve pasted the links based on our own knowledge. Check back after an hour or so, and we’re sure they’ll work normally.

Expected issues in KB3156421 & KB3156387

Update: Aaaaand yes, there are reports of minor issues in the latest updates. Do check our article before you make the leap.

Look, Microsoft does its best to ensure cumulative updates remain bug-free, reliable and don’t screw up any user. However, the nature of developing, testing, and releasing such a huge software and releasing it globally means some issues are surely going to slip past the team only to be discovered by real users.

We hope it won’t be the case with May’s cumulative updates for Windows 10, but we realistically expect this to happen. So, with that in mind, Windows Clan recommends you stay away from KB3156421 & KB3156387 for a few days. Wait for the blogosphere to report on any issues and deal-breaking bugs. If they aren’t severe and widespread, you can take the leap and download the updates.

We will be keeping a close eye on Microsoft community forums and the like for bugs and issues, and report them back to our users.

(via Windows Update History)