If you are on the beta the only way you will get the stable release is by downgrading to the last stable version 5.1.11 I believe it was and then download the stable version 9.
Got the Pie yesterday. No issues with the install.
My joy lasted only a few hours. Since the update I no longer have mobile data. Done-did the usual including a factory reset and still no luck. I'll be making a call to support once they open for calls.
Received mine the 1st day.
I believe I read that the Beta testers will eventually be provided a way to upgrade to the Pie Final version but it could be some time before that happens.
Otherwise as stated above, downgrade to 5.1.11 and then wait for the OTA for Pie.
thanks, This morning,using the one plus community forum I downgraded to the last official release and after restarting the official 9.0 release was waiting on the notification bar.
I got it maybe a half week ago. Pleased with it so far. Nothing revolutionary but definitely a solid update. Testing battery for the first time since update and I'm at close to 8 hours screen on time now over the last 24 hours (which I think might be the most SOT I've ever gotten in both this phone and any phone I've ever owned).