It seems that Samsung has issues with Oreo update for S8 and S8+, a report from AndroidPit claims that Samsung rolled back and actually stopped their update to Oreo on their flagship devices like S8 and S8+.
Samsung even release statement about this issue after users complain about the reboots.
Following a limited number of cases where Galaxy S8 and S8+ devices have rebooted unexpectedly with the Android 8.0 Oreo, we have temporarily stopped the roll out of the update. We are investigating the issue internally to ensure that the impact to the affected devices is minimized and the roll out of the update can resume as quickly as possible.
Samsung seems to be more concerned with investigating exceptions than dealing mainly with releasing devices or versions that simply work.
The company claims that limited number of users have this issue but if the company stopped the update release, it must be more then just few users who tried to update. Users who already updated their devices can continue using Oreo.
Big question that raises from this issue is, are Samsung QA their OS before releasing updates? I prefer to get my update late, but without issues.