According to @Ricciolo1, a well-known leakster, Sony plans to update its Xperia Z5 lineup to Android 6.0 Marshmallow in January with older models to receive the same treatment shortly after.
Marshmallow offers a bunch of improvements, optimizations and features that’d be welcome on any smartphone. Battery life improvements and performance boosts are the most noticeable changes to the software.
Whether or not Sony will decide to update the Xperia Z this time around is unknown but it sure would be awesome to see Marshmallow running on a phone from early 2013.
Sony Xperia z1softwear update downloading
I buy my Xperia z1 when launched in 2013 it's cost me 40000rs so pls Sony it's a humble request launch marshmallow update for Xperia z1 ...even low budget phone under 10000 rs are also.have marshmallow... So pls launch marshmallow
Becuase not all people know how to install a custom rom.