It has been four months since Google first rolled out Android 6.0 (also known as Android M or Marshmallow).  Google's own Nexus devices were the first to receive it, while very few devices from Motorola, HTC, LG, and Samsung have it.  The one Android smart device manufacturer that doesn't have it is Sony, and this is the most current information about Android M Version 6.0 Marshmallow Release Date for Sony Z5, Z5 Compact, Z5 Premium, Z4, and Z3 series and more for carriers like US Cellular, AT&T, T-Mobile, Sprint, and Verizon. 

A recent update about the Sony situation on Gotta Be Mobile has revealed that Sony has open sourced the Android 6.0 update, which will allow developers and ROM makers from the Android community to build versions of Android 6.0 for select devices.  This is supposed to speed up the already very slow process, as there are a lot of Sony device out there, many of them outside of the United States. 

It looks like those users of the Xperia Z3, the Z3V, the Z4, and the Z5 Series (the Z5, Z5 Compact, and Z5 Premium) are expected to receive more details before the end of February.  There isn't really any more detail as that. 

However, there is a report from the IB Times that the Marshmallow update will finally arrive for UK users of the Xperia Z5, Xperia Z4 Tablet, and Xperia Z3+ from the 7^th of March.  It is the first confirmation by the company after the latest update started rolling out for the Xperia Z5 to Turkish users. 

The only reason why this is known about the UK release is that Sony's UK division responded to a user of the Xperia Z3, who wanted to know when he would get his Android update.  They issued a statement saying that the company will notify when exactly each device will be getting the Marshmallow update.  It seems reasonable to assume that the most recent flagship, the Z5 series, will be receiving the update. 

If the March 7^th date is true, then it stands to reason that a global rollout will be coming, particularly in the United States.  Here is a list of Sony Xperia devices that are slated to receive the update. 

• Sony Xperia Z Ultra GPE
• Sony Xperia Z3 / Z3v, Compact, Tablet Compact
• Sony Xperia Z2, Z2 Tablet
• Sony Xperia Z5, Z5 Compact, Z5 Premium
• Sony Xperia Z3+ / Z4
• Sony Xperia C5 Ultra
• Sony Xperia C4
• Sony Xperia M5
• Sony Xperia M4 Aqua

Even if the update began to start rolling out on Sony's flagship phones, there could be an issue when it comes to the carrier.  In many cases, the some devices from subscribers like US Cellular, Sprint, T-Mobile, AT&T, and Verizon can get the upgrade before other devices.  At this present time, nothing from Sony has been updated.