Lumia 730

A critical update is rolling out to the Lumia 730, Lumia 830 and Lumia 1520 in India to fix any random reboot issues encountered by either device.

A similar update rolled out to the Lumia 930 yesterday. For those wondering, this is not Windows Phone 8.1 Update 2, but a patch to fix perioditic reboot issues:

"An important update is ready to be downloaded. Windows Phone 8.1 – This update fixes a critical issue that may cause your device to periodically reboot. Please install it now so that your phone will keep working as intended."

The update bumps the OS version to 8.10.14234.375 and the firmware version to 02040.00021.15063.02004. If you're facing the issue and are yet to see an update, Microsoft has a fix.

Source: Windows Central forums (1), (2)

Thanks Mohammed, Kavi Raj and Sadananda!