According to a recent announcement made by a OnePlus representative, it seems that the Marshmallow-based Cyanogen OS 13 will be rolling out to OnePlus One handsets starting tomorrow, the 9th of April. “Our friends over at Cyanogen have informed us that CM 13.0 (ZNH0EAS26M) based on Marshmallow will drop starting tomorrow. The rollout will be staged so only some of you (random) will get it at first, and as always, patience is appreciated.”
For those unfamiliar, the OnePlus One came with Cyanogen OS installed, versus the OnePlus 2 and the OnePlus X which came with the company’s own OxygenOS. While the update was promised for tomorrow, there have been some users who have confirmed that they have actually received it today.
In any case if you haven’t received yours yet, don’t worry as updates are usually rolled out in stages, so even if you don’t see it tomorrow, you should be able to get your hands on it in the next few days, so keep an eye out for it.