If you use the English language, please use google translate (from vietnam to english).
Sorry for my english.
"Although the company has announced the updated schedule for the Xperia models a week ago, however many may have noticed so far have not posted an update.
According to sonyfan information, just before the release, the company has detected a number of software bugs, including poorly managed RAM causes overflow of RAM, can affect the performance of the device, cover user experience. Therefore, the update plan has been delayed from the original about 1 month, giving time error correction and optimization.
Currently, the update of Android Pie 9.0 for XZ2 is not really as expected, some still complain about the problem of network connection, battery drain, fingerprint sensor sometimes not effective, ... To avoid trouble playback born with a group of users of old machines, the company's move is able to sympathize."