Microsoft Fixes the Disappearing Messaging App Issue in Windows 10 Mobile 10536

Microsoft has now fixed the issue that was discovered in the Windows 10 Mobile build 10536 where the Messaging app would disappear after a hard reset to the new build. 

There are various known issues in the test build as shared with our readers earlier, but these kind of errors and issues are always expected in the testing builds.

A service-side fix has now patched the issue which means if you do a hard reset after upgrading to the Windows 10 preview build 10536, you won’t lose the Messaging app. Gabriel Aul of Microsoft suggests that if you have already installed the test build, you will have to flash it again if you had lost the app.
Windows 10 Mobile build 10536 introduces an updated Photos app and one-handed mode for all devices, among other features enhancements. 

You can read all about this build in our detailed post. Other known issues with the Windows 10 Mobile 10536 build include:
After rebooting your phone, you won’t see notifications, such as new messages, until you unlock your phone. After that, you should see notifications for new messages just fine. “zStorage” appears in the Settings app under System and clicking on it causes the Settings app to crash.
Camera upload to OneDrive may not be enabled based on prior settings. To fix this, make sure you are running the latest version of OneDrive by opening the top left navigation bar, then settings on the right to verify that camera upload is turned on and you have the latest app (version 17.2).

Insiders will not be able to move from Slow to Fast rings temporarily; we are working on a fix but in the interim to move a device from Slow to Fast you will need to use the Windows Phone Recovery Tool to first start on Windows Phone 8.1 and opt directly into the Fast ring.
Additional languages for speech and keyboards won’t be available until tomorrow (9/15) and will error if you try to download. If you already have languages for speech and keyboards downloaded to your phone prior to upgrading, they will remain and available to use.