In last October, Sony revealed that six of their devices wouldn’t receive update to Android 5.1 Lollipop and instead, these smartphones will jump to the Marshmallow 6.0 version. One smartphone that it’s on this list is the Sony Xperia C4 so probably this device will have a taste of Marshmallow soon.
Now there’s an update out for it but it’s not Android 6.0. It’s Android 5.1 Lollipop, a version these models shouldn’t have received.
The rollout is currently underway for five of the six C4/C4 Dual versions out there, just the E5343 was excluded for now.
The update will reach your device via OTA, probably within the next few days. After having installed the new release, you’ll be on build number 27.2.A.0.155 for the C4, or 27.2.B.0.155 for the C4 Dual.