I didn't notice I had an update until a last week... and boy was I upset after I accepted it. I can't believe how bad the changes are as they completely affect the ease of using the phone. Multi-window was perfectly implemented before...a couple taps and easy to juggle apps. Now you have to do multiple steps which involve visually hunting for a small items.... even worse when trying to select a single line of small text in a list of pop up items. And trying to get Google maps navigation to work in a specific half of the screen is completely counter intuitive because it would rather be in a pop out window.
And don't get me started about how you must shift to use the comma on the keyboard or swipe to use video instead of pushing a record button on the photo modes
Samsung is censoring this forum. YOU CAN ROLLBACK to Oreo.. just google the youtube video. It's a clean rollback with odin and does not trip any flags.. thousands have done it.
Took me about 5 hours but was able to get back my beloved OREO using odin and the sammobile flash files. Most of my settings gone but was able to save all my data.. Amazing thing is it's like a new phone, fast, and the firmware on the sammobile site was a better version of oreo somehow I'm getting all these new cool options I didn't even know about!
I swear, downgrading to OREO is like actually upgrading the phone! I have a note 8 korean KT Emperor Edition 256GB internal.
@Nessie1is correct. Whether or not the flash is flagged by the device, unauthorised modifications to the OS render the warranty void, and might affect the device's compatibility with future updates.
You're not modifying the software, you're simply reinstalling the official software that was on the phone when you bought it.
Rooting the device can void the warranty but that's a different thing.