Days after its first foldable went on sale Friday, Apple acknowledged an inner-display problem and told affected owners to contact AppleCare for a replacement. "We are aware of an issue impacting the inner display on a small number of iPhone Duo units," a company representative said, per CNBC.

The £1,999 ($2,668) phone drew crowds at Apple stores worldwide, and initial online orders sold out within minutes. Owner reports describe bright horizontal lines and cracks near the hinge, sometimes within hours of unboxing — a wave of negative publicity The National dubbed "crackgate."

The Duo was pitched as the foldable that would get the form factor right, and Apple's new chief executive John Ternus had claimed rivals built devices that "just feel like two phones awkwardly stuck together."

Yet even Apple's engineering resources and supply chain discipline "face a steep learning curve in foldables," as IDC analyst Francisco Jeronimo put it to the BBC.

A screen that can crack in under a day — one Australian buyer per the New York Post reported damage after six hours and fewer than 20 openings — undercuts the premium positioning Apple spent years developing.

Photos posted on Reddit and X show damage concentrated around the hinge, with bright lines running toward the right edge and dead pixels along the crease.

The New York Post reports one Reddit user in Dallas said the hinge tightened after a few folds during setup, then popped loudly; an Apple Store swapped the handset on the spot at no charge.

Apple's Alex Kirschner reportedly said defects appear very quickly on affected units, according to Ars Technica, so owners won't wonder if their phone is a ticking time bomb. The Verge also relayed Apple's statement to Bloomberg and 9to5Mac.

With Apple silent on a cause, iFixit's teardown is the closest thing to an explanation.

Using CT scans, iFixit found the failure point sits below where the display's ribbon cable passes through the hinge, where the support mechanism narrows; the support bar may stick, preventing the waterdrop bend the OLED needs when the phone closes. iFixit CEO Kyle Wiens wrote on X that the hinge is "dozens of parts, with ludicrous precision" and that "a manufacturing variance or grain of sand can kill the fragile display panel it protects."

The firm also called the Duo the easiest-to-repair foldable it has tested.

Apple lists an out-of-warranty inner-screen repair at $999 on its website — roughly half the Duo's starting price — per CNBC, which is why routing early failures to replacements matters.

Analysts say buyer confidence in the whole category is on the line: Jeronimo told the BBC that because Apple positioned the Duo as a "premium alternative," how it handles this first-generation issue will shape confidence well beyond its own sales.

"At $1,999, confidence is part of the product," RKS Design founder Ravi Sawhney told the New York Post, warning that hesitation at the fold could extend to foldables generally.

Apple still has 28 further markets launching on October 30, and Jeronimo says it needs to clarify its warranty position quickly before then.

Apple also struck an upbeat note, saying the response from early users has been "incredibly positive" and that developers are rapidly updating apps for the form factor.