For the first time, Sony has released the first over-the-air update for its Xperia XZ1 and Xperia XZ1 Compact. This update brings the build number to 47.1.A.2.374 from 47.1.A.2.324. It brings with it the latest October 1, 2017 Android security patches. But beyond that we’re not sure what else is being offered in the update. If the OTA update doesn’t show up on your device immediately, be patient. Roll outs for these usually take a bit of time.
Source: GSMArena