SAN FRANCISCO: Days after launching its first folding iPhone, Apple acknowledged on Monday that some of the ‌devices exhibit display problems and said it will replace them.

Apple started shipping the iPhone Duo last week, with customers around the world lining up for tight inventory after initial online orders sold out in minutes. Analysts have said Apple is likely to face supply constraints because the iPhone Duo, which ⁠unfolds like a passport booklet, is complex to manufacture.

Over the weekend, social media posts showed the iPhone Duo with cracks and lines in the inner display along the central hinge where the iPhone Duo folds.

Apple ‌acknowledged the problems on Monday, saying affected units tend to show the problem quickly.

"We are aware of an issue impacting the inner display on a small ‌number of iPhone Duo units," Apple said in ‌a statement. "If users experience issues with their iPhone Duo display, they should ‌contact AppleCare for a replacement."

Apple ‌did not comment on what might cause the issue.

iFixit, a firm that publishes teardown reports of electronic devices along ‌with guides on how to repair them, said it ⁠used teardown footage, patents and CT scans to construct a 3D simulation of the iPhone Duo hinge that it compared with the reported damage locations.

iFixit said its simulations found ⁠the reported damage clustered ⁠just below where a display cable runs under the screen near a central support bar. That bar might be failing to drop out of the ⁠screen's way as the phone is folded, "creating a small stress hotspot near the reported break location," the company said.

Apple did not immediately comment on iFixit's findings, which also concluded that the iPhone Duo is the most repairable foldable phone that it has tested.

Francisco Jeronimo, a vice president ‌at market research firm IDC, said Apple's quick replacement offer was the "right first step" in responding to the problems.

"We all remember when Samsung experienced problems with the original Galaxy Fold in 2019, but it also showed that a fast and transparent response can contain the damage to a category," Jeronimo said.

iPhone Duo cracks and lines: Apple says it will replace units showing screen problems