Apple has acknowledged a problem with its first foldable phone, the iPhone Duo, after a series of reports of inner screen damage, and said it will offer replacements.

On Oct. 26, Apple and overseas media including CNBC said Apple confirmed inner display issues on some devices and told customers they can get replacements through AppleCare.

The iPhone Duo began in-store sales on Oct. 23 and drew strong early interest, with a surge in pre-orders and lines at stores. But from the first weekend after launch, users began reporting broken screens. Some said a bright horizontal line appeared near the hinge or the screen cracked after folding or unfolding. Some devices also reported pixel damage along the fold.

An Apple spokesperson said the company is aware of an issue affecting the inner display on a small number of iPhone Duo devices. The spokesperson said users who experience screen abnormalities should contact AppleCare to request a replacement. Apple did not disclose the exact scale of damage or the cause. According to Apple's website, repairing the inner screen on an out-of-warranty device costs $999, or about 1.3 million won.

Many of the reported cases appeared on online communities such as Reddit and X, formerly Twitter. But false images are also circulating online, and not all cases have been confirmed as actual damage. Teardown and repair firm iFixit said after disassembling the product that the hinge design may have contributed to the breakage.

Shahram Mokhtari (샤람 모크타리), a technician at iFixit, said in a teardown video that some users continued applying force even after hearing what sounded like something breaking while folding or unfolding the device. He pointed out that the hinge structure in the area where the damage occurred appeared to differ somewhat from other parts. Kyle Wiens (카일 빈스), iFixit's chief executive, also said on X that the hinge is made up of dozens of precision parts and that manufacturing variances or even a single grain of sand could damage the inner display. Apple has not officially confirmed whether there is a hinge defect.

Problems have been reported on some devices, but the same phenomenon has not appeared on all products. The issue was not found on Engadget's review unit or on a device obtained by CNET. Engadget reported that a hinge durability test on a specific device performed more than 55,000 folding actions.

Inner screen breakage in foldable phones is not a new issue. In 2019, early foldable phones from Samsung Electronics also drew reports of screens cracking during normal use, and durability was cited as a major obstacle to wider adoption. This case has also revived concerns over the durability of foldable device screens and hinges.

Early user reviews included positive evaluations of multitasking and media use when the iPhone Duo is unfolded. Some also raised concerns that certain applications are not sufficiently optimised for the larger screen. Apple said initial user reactions are positive and developers are updating apps quickly to fit the new form factor.

As a result, the iPhone Duo's early success is expected to depend more on durability responses and the speed of app optimisation than on simple sales volume. Apple has moved first to address early complaints with a replacement policy, but the cause of the breakage and the extent of its impact remain key variables going forward.

The hinge is actually dozens of parts, with ludicrous precision. A manufacturing variance or grain of sand can kill the fragile display panel it protects. https://t.co/UuQR4F6Per