Microsoft's new Windows 10 beta build for phones fixes pesky upgrade bug

New software brings performance improvements, but no new features

Windows 10 Mobile running on a Lumia 640 XL.

Windows 10 Mobile running on a Lumia 640 XL.

Credit: Blair Hanley Frank

People who have been testing the latest beta versions of Microsoft's Windows 10 for smartphones have a new operating system build to play with Thursday. The company began rolling out build 10581 of Windows 10 Mobile to members of the Windows Insider Program's fast ring who are trying out the cutting-edge updates Microsoft has been making available to the public. 

This build doesn't have anything in the way of new features over its immediate predecessor, but Microsoft general manager Gabe Aul listed a whole bunch of performance improvements and bug fixes coming to the operating system. The biggest fix is that this build finally allows people who were running build 10536 of Windows 10 Mobile (which was released last month) to update directly to the new version without requiring them to first erase their phone and re-install Windows Phone 8.1.

Microsoft released two builds earlier this month that couldn't be directly upgraded from 10536, which meant users had to go through a massive rigamarole in order to get onto the latest OS if they wanted it. 

On top of that fix, the new software is supposed to bring battery life improvements, thanks to several bug fixes focused on making phones last longer on a single charge. That's an important move for Microsoft, as the official release date for Windows 10 Mobile grows ever closer. It's supposed to be the operating system powering the new Lumia 950 and 950 XL, which are slated for release next month. 

As per usual, there are some known bugs in this release, including a couple of issues relating to storing files and applications on SD cards. Users won't be able to set their default save location, and SD cards they have installed will show up with their names garbled. Defaults that they set previously to the update are supposed to remain the same, however. Also, installing apps on a phone's SD card may cause the application to crash when first opened. Users should be able to fix that problem by restarting affected phones. 

In addition to the mobile news, Microsoft is also planning to push a new beta for Windows Insiders who are using the new operating system on their desktop computers and tablets later in the day on Thursday. According to Aul, it's the first time the company has released both a mobile and desktop beta build on the same day. 

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