Apple's new iOS 11 software for iPhones and iPads rolled out yesterday, but its adoption is slightly slower than that of its predecessor, and, as is often the case, various issues have been reported by early adopters.

iOS 11 had been installed on just over 10 percent of supported devices in the 24 hours after it went live, according to data from Mixpanel. That's slightly slower than adoption of iOS 10 at launch (which was just over 14 percent after 24 hours). Tech wisdom has long held that people are generally wise to hold off installing major new OS releases until a couple of iterations in. However, Apple has always prided itself on its users' rapid adoption rate of new software releases, citing it as a metric in past conference keynotes and reports. This is still a good pace of adoption for the industry, but a handful of issues could explain the slower movement.

In fact there may be one big issue and a few smaller ones. Most of the issues are likely to be resolved in a short time, but there are a few that we'll have to get used to. You've probably already read about the Apple Watch Series 3's LTE connectivity problems—that's an example of something that will get fixed for later adopters. What follows are some of the iOS 11 problems on iPhones and iPads.

Disabling Bluetooth and Wi-Fi in the Control Center

In the previous version of iOS, tapping the Bluetooth button in Control Center—the one-stop shop interface for basic phone functions like brightness, volume, and connectivity—completely disabled Bluetooth on the phone, but that is not the case in iOS 11, perplexing many users. According to our tests and a support document from Apple, disabling Bluetooth connectivity from Control Center only disconnects currently active Bluetooth pairings and prevents new pairings until it's re-enabled. But the Bluetooth hardware is still going. The same is true of Wi-Fi.

Apple implies in its support documentation that this is to ensure that some of what it may consider core iOS services like AirDrop, AirPlay, Apple Watch, Apple Pencil, Continuity, Instant Hotspot, and Location Services will continue to function. In a vacuum with no user expectations, this could be a reasonable design decision. That's because Bluetooth's battery impact is negligible when it's not actively used with another device, so keeping those services alive while still allowing the user to avoid connecting to nearby devices, and draining the battery life doing so, will produce the best outcome for the majority of people, though edge cases may exist.

However, those user expectations are a sticking point. To Apple's credit, it clearly outlined this functionality in its support documentation, but iOS users have been trained since 2013 to believe that tapping that Bluetooth button in the Control Center will turn Bluetooth off completely. That is no longer the case, and for a company that at one time made a lot of noise about intuitive user experiences, it's a surprising choice to make this change without more clearly signifying it in the user interface.

This is one of the handful of iOS 11 adoption pains that probably won't go away with future updates, but it's important to note that it's still possible to turn off Bluetooth. Apple's documentation says—and we confirmed this by testing it—that disabling Bluetooth in the Settings app really does turn it off. Furthermore, we tested the Airplane Mode button in Control Center and found that tapping that did indeed disable both Wi-Fi and Bluetooth. There are now essentially more options for users when it comes to managing wireless activity on the phone, but the implementation is confusing at best. In the end, it's unlikely to be a significant inconvenience to most users, but it's worth knowing about it, regardless.

Outlook, Exchange, and Office 365 e-mails might not send

There's an issue with e-mail that is much more serious. Users relying on e-mail accounts hosted on Outlook.com, Office 365, or Exchange Server 2016 might receive an error message when trying to send an e-mail in iOS 11: "Cannot Send Mail. The message was rejected by the server." Apple and Microsoft have both stated they are aware of the issue and expect it to be fixed in a future iOS software update.

Naturally, Microsoft says you can work around this by switching to its own Outlook mail app for iOS. But if you want to stick with what you're already using, you'll be waiting for a patch. These are very popular mail servers, so it's surprising that this issue made it to the final launch. But surprise or not, this supports the argument that you should be cautious before adopting a major new OS release on a device you depend upon.

The big one: 32-bit app support

As we mentioned when iOS 11 launched, this update drops support for 32-bit apps, so several of your old apps may stop working when you upgrade. iOS 11 will refuse to launch them, with an error message saying: "The developer of this app needs to update it to work with iOS 11." Whether you're using iOS 10 or iOS 11, you can find a list of currently installed apps that will stop working by opening the Settings app, then navigating to General, About, and Applications. For some users, of course, there will be very few or even no unsupported apps, but for others it could be dozens.

Apple started warning developers to update their 32-bit apps and recompile them for the 64-bit architecture some time ago. For some apps, this could be easy to do. Others could run into unexpected problems. In any case, the reality of the world of mobile apps is that many are not supported after they initially launch—especially games that are not based around online services, like Sid Meier's Pirates! or Costume Quest. Whether they're working independently or within an organization, app and game developers move on to other projects. In some cases, game publishers may have completely disbanded the teams that made the games, and there is no one who holds the responsibility of keeping things up to date with new iOS developments.

The list of soon-to-be-broken apps on my phone shrank significantly in the weeks leading up to iOS 11's launch, and some of the stragglers may yet get updated. But others never will. This issue, then, is both a growing pain and an early adoption problem. On one hand, you can expect the problem to get a little bit better over time as more apps are updated. But on the other, some apps that are lost will never be found again.

Apple didn't handle all of these issues perfectly. The Exchange bug is particularly problematic. But to some degree, we're seeing Apple struggle with many of the same problems in iOS that Microsoft, for example, has dealt with in Windows for years.

That is to say that some dosage of conservatism becomes necessary with a mature platform. Breaking common use cases (Exchange), fighting against established user habits and expectations (Bluetooth), and discontinuing support for old technology (32-bit apps) are all problems platform owners have faced before in a mature marketplace. And for better or worse, the smartphone marketplace is now as mature as it gets. So as Windows users have been saying for a lot longer than the iPhone's single decade: pick your upgrade timing carefully, and maybe wait for a couple of patches.