Microsoft has begun rolling out the April cumulative update for Windows 10 Mobile. As with most cumulative updates, it doesn"t contain any new features, but it does contain fixes.
Here"s the change log:
Reliability, performance and stability improvements.
Support for Visual Voicemail on Dual SIM phones.
Improvements for Bluetooth connectivity, including the reliability of connecting to and staying connected with Bluetooth devices.
Fix for a problem that caused audio playback to get occasionally interrupted in Groove Music and other music apps when phone display was turned off.
Improvements for Microsoft Edge browser, including support for configuring a prompt before a file download occurs, support for background downloads, and a fix for a problem where opening a link from an another app wouldn’t load the web page.
Reliability improvements for Cortana reading text messages aloud and usability improvements for Quiet Hours feature.
Improvements for Store reliability, including a fix for a problem that prevented some apps from being updated and installed.
Fix for a problem that occasionally caused some apps to show blank tiles after upgrading from Windows Phone 8.1.
Improvements for PC connectivity via USB on some phones that were upgraded from Windows Phone 8.1.
The update is available to both the Production ring and the Release Preview ring; however, it"s important to note that cumulative updates are no longer rolling out through the Slow ring, as that is reserved for Redstone builds now.
It"s also worth noting that the update is available for devices that aren"t officially supported for the Windows 10 Mobile upgrade. Those devices can still get updates through the Release Preview ring for the time being.
Source: Microsoft Answers