Google has released its latest Android 6.0 Marshmallow OS for smartphones, but some handsets have not yet upgraded to this new operating system. Motorola published its list of devices that will be receiving the latest Android 6.0 Marshmallow update. However, the list does not include some handheld devices that consumers have been expecting.

Motorola's list of smartphones scheduled to get the Android 6.0 Marshmallow upgrade includes: the 2015 flagship Moto X Pure Edition (Gen 3), Moto X Style (Gen 3), 2015 Moto X Play, Moto G (Gen 3), 2014 Moto X Pure Edition (Gen 2), 2014 Moto X (Gen 2) specific to Latin America, Europe and Asia, 2014 Moto G, Moto G 4G LTE (Gen 2), 2014 Moto Turbo, 2014 Moto MAXX, Motorola Nexus 6 and DROID Turbo.

The first batch of Motorola smartphones to get the OTA notification is the Moto X, Moto G 2015, and Moto MAXX, according to Tech Times. But the report added that all of the 2015 Moto X models will reportedly get Marshmallow very soon. Owners of lesser range Motorola models from last year should not fret as their handheld devices will also be getting the Marshmallow upgrade.

Tech times said, "While the 2014 Pure edition made the cut, unfortunately neither the AT&T or Verizon 2nd gen Moto X will be invited to the Marshmallow party, much to the chagrin of owners of those devices. The original Moto G and Moto X won't receive the update either, nor will any of the company's Moto E devices."

In the meantime, Motorola has started to initiate the release the latest Android 6.0 to several users to test the new OS via the Moto X Pure Edition (2015).

The International Business Times has confirmed that Motorola is presently testing the firmware "that will be followed by a soak test. It will be then eventually rolled out for general users." However, the tech giant is still mum about the exact date of the Android 6.0 rollout for its handsets.

Mobile phone owners who want to upgrade their smartphones to Android 6.0 are advised to make sure that they still have sufficient memory space. Android 6.0 is at least 500 MB in size.

The IBT added, "With the release of the new OS, going forward Motorola will preload its devices with Moto Assist, Moto Migrate and Motorola Connect as it will replicate features of the Android version 6.0 including Do Not Disturb (DND) and automatic data backup."

But older Motorola models will not have mobile OS update, even some of those that were released just last year. Android Central's Phil Nickinson had earlier called Motorola out to stop selling the Moto E if the company cannot commit to updating it.