• Apple said on Saturday that it will issue a software update that would address customer complaints about the latest iPhone 15 models, released just over a week ago, running hot.
• Apple said that the new iPhones were running hot because of a combination of bugs in iOS 17, bugs in apps, and a temporary set-up period that requires extra processing and therefore heat generation.

Apple said on Saturday that it will issue a software update that would address customer complaints about the latest iPhone 15 models, released just over a week ago, running hot.

Apple said that the new iPhone models were running hot because of a combination of bugs in iOS 17, bugs in apps, and a temporary set-up period.

An Apple spokesperson told CNBC:

"We have identified a few conditions which can cause iPhone to run warmer than expected. The device may feel warmer during the first few days after setting up or restoring the device because of increased background activity. We have also found a bug in iOS 17 that is impacting some users and will be addressed in a software update. Another issue involves some recent updates to third-party apps that are causing them to overload the system. We're working with these app developers on fixes that are in the process of rolling out."

After Apple released the new iPhone 15 models earlier this month, user complaints on Apple's forums, Reddit, and social media suggest that all four models can get hotter than expected during use. CNBC's review of the new iPhone Pros also noted the iPhone 15 Pro Max got hot.

"I just got the iPhone 15 Pro today and it's so hot i can't even hold it for very long!" wrote one commenter on Apple's forums.

Apple's new high-end models, the $999 iPhone 15 Pro and $1,199 iPhone 15 Pro Max have a redesigned titanium enclosure with an aluminum frame to make them easier to repair. The problem with the new models overheating was not related to the titanium chassis design, Apple said.

Instead, Apple points to bugs with specific apps and a bug in iOS that can be fixed with software updates. Apple said that a forthcoming iOS 17 update to address the issue won't reduce the performance of the devices.

Apple's website says that users may notice phones feeling warmer when they're set up from a backup, when they're wirelessly charging, using graphics-heavy apps or games, or streaming high-quality video. Apple says that it's normal for devices to be warm when they're being heavily used, and if iPhones don't display a temperature warning, they're safe to use.

Still long lines

So far, the new iPhones appear to be selling well, with ship times for the devices sometimes stretching out for weeks, and long lines appearing in front of Apple stores on launch day.

"Interestingly, lead times for the 15 Pro Max, 15 Plus and 15 are tracking more elevated relative to their predecessors (e.g., iPhone 14 Series), and the 15 Pro Max is boasting the highest lead time we have seen historically across all SKUs since we have been tracking lead time data," JPMorgan analysts wrote in a note last week.

But one notable Apple supply chain analyst, Ming-Chi Kuo, said last week in a blog post that the iPhone 15's heat problem could hurt sales.

Apple has faced high-profile launch issues in the past but they haven't seriously impacted the company's long-term outlook.

The iPhone 4, launched in 2010, had a design flaw that could lead to calls being dropped. Apple offered free cases to ameliorate the problem. In 2012, shortly after the launch of the iPhone 5, Apple CEO Tim Cook apologized for Apple Maps being buggy and unreliable. The iPhone 6 released in 2014 was criticized for bending under pressure.