Hi everyone,

Today we are rolling out Windows 10 Mobile Insider Preview Build 10581 to Windows Insiders on the Fast ring. We’ve fixed the bug preventing upgrades from earlier builds. So if you stayed on Build 10536 or if you flashed back to Windows Phone 8.1 and then installed 10549 or 10572 you can upgrade directly to this new build without going back to 8.1 again. This build doesn’t have significant new features but does include a bunch of good fixes and general performance improvements.

Here are some things we have fixed:

For devices upgraded from Windows Phone 8.1 like the Lumia 930, Lumia Icon, and Lumia 1520 that had the “Hey Cortana” feature – with this build “Hey Cortana” should work again in Windows 10. To make sure it’s turned on, just go to Settings > Extras > Hey Cortana.

You can now select photos for sharing through third party apps like Facebook, Facebook Messenger, Instagram Beta, WhatsApp etc.

Battery life should be improved in this build. We fixed several bugs impacting battery life.

We fixed an issue where you couldn’t choose some apps to show quick status on the Lock screen via Settings > Personalization > Lock screen.

We’ve made improvements to text prediction and auto-correction.

Video recording functionality has been improved.

Visual Voicemail sync should now work properly.

We fixed the dual-SIM issues that appeared in Build 10572.

We fixed the issue found with Build 10572 where the Chinese Pinyin QWERTY keyboard stopped working after upgrading from Windows Phone 8.1 that our Chinese Windows Insiders reported.

Known issues:

As with previous builds, after applying this update the device may appear at a black screen for about 5 minutes when transition between the spinning gears and the final stages of update. Just be patient and it should progress past it. Exact time will vary by device.

You will be unable to set your default save locations via Settings > System > Storage and will not correctly reflect the current storage settings. If you are using a SD card in your phone, it will show up as a garbled name in Storage settings. Whatever you had configured for your save locations in the previous build will be the same.

After moving some apps to a SD card, those apps might crash. The workaround is to reboot your phone and those apps should work fine thereafter.

Deploying Silverlight apps through Visual Studio to your phone won’t work in this build. You can deploy UWP apps to your phone without any issues.

If you restore a backup from a phone that had a different resolution, you may end up with a corrupted Start experience. The workaround is to go to Action Center (which won’t be corrupted) then Settings > Personalization > Start and apply a different background picture.

We’re very happy to have the upgrade bug behind us which caused a few unusual flights, and are hugely appreciative of the Windows Insiders who did the extra work to re-flash and try those builds. For those of you who chose to wait it out, we hope you’ll find this build worth the wait.

Thanks,

g