Microsoft releases Windows 10 Mobile Insider Preview build 10586 to the Fast ring

It's been three weeks since the last Windows 10 Mobile Insider Preview, build 10581, rolled out to users on the Fast ring. Today, Microsoft has released build 10586 for Fast ring users, promising "lots of good bug fixes and general improvements for you to check out."

As with Windows 10 for PCs, build 10586 is expected to be the final Insider Preview - effectively the 'RTM' build (although Microsoft no longer uses that terminology) of the OS - before its official launch. Windows 10 Mobile will make its first 'real world' appearance on the company's new Lumia 950 and 950 XL flagships in the coming days, before it begins its rollout to other devices next month.

It's perhaps not surprising, then, that Microsoft's Gabe Aul says that 10586 "is a really great build", but before you install it, be sure to check out all of the known issues, as he warns:

@GabeAul Please make sure you read the post - there is an issue that some of you are likely to hit. Back up before installing!
— Gabriel Aul (@GabeAul) November 18, 2015

Here's the full list of known issues in the new build, including that important one that Gabe highlighted:

After we released Build 10581 to Windows Insiders in the Fast ring, we discovered a bug in the build that will cause the filesystem to become partially corrupted after doing a factory reset. For those of you who did a factory reset of your phone, you most likely did not notice this issue on Build 10581. Due to this bug however, upgrading to Build 10586 will cause your phone to go into a reboot loop after the upgrade completes – rebooting at the Windows or operator logo. To recover your phone, you can use the hardware key combination to reset your phone which will then put it at the OOBE experience on Build 10586. We highly recommend that you make sure you do a backup your phone *before* upgrading to Build 10586 due to this bug. Additionally, you can also recover your phone by using the Windows Device Recovery Tool to go back to Windows Phone 8.1 and then upgrade to Build 10586.

Deploying Silverlight apps through Visual Studio to your phone still won’t work in this build. This issue will be fixed with the release of Visual Studio 2015 Update 1 on Nov. 30th. You can deploy UWP apps to your phone without any issues.

There is a known issue where the tile for Insider Hub still remains under All apps but doesn’t open. Insider Hub isn’t included in this build. There isn’t a way to get it back unfortunately. However, it’ll return in a future flight! In the meantime, use Insider Hub on the PC as a workaround.

But the good news, as ever, is that Microsoft has also fixed a range of other issues in its latest release:

We have fixed the issue that caused the Start experience to become corrupted (garbled) after upgrading and restoring a backup from a phone that had a different resolution.

You should now be able to set your default save locations via Settings > System > Storage and it will correctly reflect the current storage settings. Your SD card should no longer show up as a garbled name in Storage settings either.

Moving apps to a SD card should no longer cause those apps to crash.

We’ve made improvements to the Messaging + Skype app – through both app updates via the Store and also on the server side.

This should be seeing less resuming/loading text when switching apps.

The physical camera button should be working again if it wasn’t working for you before.

Apps and games should download from the Store more reliably.

As ever, if you install the new build, be sure to let us know how you get on in the comments below.