Last year, a change to the Android 11 Vendor Test Suite was spotted, indicating that phones launching with Android 11 and later would be required to support so-called "seamless" updates. This feature allows a phone to install a system update while it's running and simply reboot into the new environment without any user-facing delay. Unfortunately, that hasn't panned out. According to the latest Android 11 Compatibility Definition Document (CDD), Google has seemingly walked back that requirement, and we can confirm that the Samsung Galaxy S21 doesn't support seamless updates.

For those unaware, Android has supported a process called seamless updates since 2016. There are a few different ways to implement it, like virtual A/B partition support, but the very short version is: it lets the phone install an update while it's being used. You don't have to sit for ages waiting on some progress bar in your bootloader, staring at a phone that can't even make emergency calls. The systems behind it also reduce the chance that an update can go wrong, making it easier to revert. It's not even a premium feature, and tons of Android phones from manufactures like Google, Motorola, OnePlus, and even LG support it. But now, coming up on half a decade since the feature was revealed, Samsung still doesn't support seamless updates on its phones.

S21 owners can look forward to sitting and waiting on this screen once a month as updates are installed. 

The omission has been contentious for us here at Android Police since last year when the super-expensive Galaxy S20 series debuted without the (to us, very basic) feature. Since Samsung has become one of the most timely phone manufacturers when it comes to updates, that is a double-edged sword. Yes, Samsung phones get exceptionally timely monthly security updates now, which is unarguably a good thing. But, it also means Samsung phones spend a lot of time as useless bricks while installing those updates over their lifetime. It is a minor point of frustration, but a legitimate one when so many other devices support it, especially at the sort of premium prices Samsung charges.

Initially, we thought Google had put its foot down about the practice last year when a change to the Android Vendor Test Suite indicated that virtual A/B partition support would be a requirement. Mishaal Rahman of XDA Developers also confirms seeing an early draft of the Android 11 CDD, which stated that seamless updates would be required for phones launching with Android 11. However, according to the latest January 2021 version of the Android 11 CDD, seamless updates are not a requirement, and Google is only telling manufacturers that they "should" support it. It would appear that Google has walked that requirement back, perhaps under pressure from smartphone makers like Samsung.

Excerpt from the January 20th 2021 Android 11 CDD stating phones only "should" support A/B system updates — as in, they don't absolutely have to. 

We can confirm that seamless updates are not present on our Galaxy S21 Ultra review unit, and AP's Max Weinbach has further confirmed the omission in a quick teardown. We've reached out to Google for more information regarding its seamless updates policies and to Samsung for an explanation regarding why its new S21 series still doesn't support seamless updates.

Whatever the rationale or logic behind the decision might be, Samsung's new $1,200 Galaxy S21 Ultra is missing a basic and time-saving feature that many cheaper phones have.