Older OnePlus devices won’t get Pie for a while
OnePlus CEO Pete Lau reported on his Weibo page that the company won't be able to deliver the Pie update to their OnePlus 3/3T and 5/5T model just yet. It is deserving of comlipents that the company even announced their plan to push the new iteration of Android to their 3/3T phones which are now already more than 2 years old and it is perfectly understandable that some tweaking has to be done, it is uncleas as to why the 5/5T generation needs more time.

Sadly, Lau didn't provide any more information, but he did go on to tease the OnePlus 6T. As he said, the 6T will out-of-the-box come with Android Pie preinstalled on top of which we expect to see the new version of OnePlus's OxygenOS UI. We can just hope that the earlier OnePlus phones will get their updates soon.
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