Microsoft is now rolling out the Windows 10 Mobile preview build 14291 to nearly all of the devices that are able to receive updates from the Windows Insider program. The one exception is the Lumia 635, which will get the build at a later date.

Users will need to be on the Fast ring to see the update.

Build 14291 is part of the new Redstone branch, which is set to unify OneCore and bring new native features to Windows 10. Previously, only a subset of new Lumias that launched with Windows 10 Mobile were eligible for the preview update.

Being an early preview, it is not yet advised to use on your main phone unless you understand and are okay with the associated bugs and issues (see below).

Microsoft's Windows Insider head Gabriel Aul stated

"Going forward – these devices can receive new builds from our Development Branch that we release to the Fast and Slow rings. As we stated previously, only devices which are eligible to receive the Windows 10 Mobile upgrade will be able to get preview builds from the Development Branch."

As a reminder, here is that list of eligible Insider devices:

  • Alcatel OneTouch Fierce XL
  • BLU Win HD W510U
  • BLU Win HD LTE X150Q
  • Lumia 430
  • Lumia 435
  • Lumia 532
  • Lumia 535
  • Lumia 540
  • Lumia 550
  • Lumia 635 (1GB)
  • Lumia 636 (1GB)
  • Lumia 638 (1GB)
  • Lumia 640
  • Lumia 640 XL
  • Lumia 650
  • Lumia 730
  • Lumia 735
  • Lumia 830
  • Lumia 930
  • Lumia 950
  • Lumia 950 XL
  • Lumia 1520
  • MCJ Madosma Q501
  • Xiaomi Mi4

For more information on build 14291 see below:

What's Fixed for Mobile

  • We fixed the issue where connectivity to older Wi-Fi networks using the WEP encryption security method may be broken.
  • We fixed an issue resulting in slower text input speed the more words were typed.
  • We have improved Word Flow recognition of longer words.
  • The All apps list has been updated to now follow the "Make Text Larger" ease of access setting.
  • We fixed an issue where Settings would sometimes list unresolved app names under Extras.
  • We fixed an issue where touch targets could be out of alignment in the Photos picker.

Known Issues for Mobile

  • If you reset your phone on this build (Build 14291) and restore your phone from a backup, restore will fail to install apps from your backup's apps list leaving blank grey titles on Start. If you delete the grey tiles and attempt to reinstall the same apps from the Store, you will not get app data restored. The next backup will over-write the app backup data as well. To avoid hitting this bug, avoid resetting your phone on this build. If for some reason you do need to reset your device on this build, don't restore your phone from a backup and you should turn off backup for apps and OS data to avoid creating a corrupt backup via Settings > Update & Security > Backup.
  • If you have a Microsoft Band 1 or 2 paired to your phone, it will no longer sync after updating to this build due to a system API failure that occurs after the update. If you want to get your Band syncing with your phone again – you can temporarily change the language of your phone as a short-term workaround until we release a fix. Additionally, you can also choose to reset your phone to get out of this state – however you may experience this update issue again with the next build until we fix this issue. This issue may also impact Skype video and audio calls.
  • The Gadgets app will not detect the Microsoft Display Dock on phones running Windows 10 Mobile Insider Preview builds, and thus cannot update the firmware version. If you have a dock which has already been updated to version 4 then this will not affect you. If you have a dock that has not been updated, then you may experience some minor issues with USB-C stability. You will still be able to use your dock and Continuum.
  • There is a new option under Settings > Update & security for Windows Insider Program. This is a work-in-progress option to improve managing your Windows Insider Program settings on your device. Right now, if you go to this option it crashes the Settings app. Please continue to use the Windows Insider app to manage your settings for now.