We now know Angela Ahrendts isn't to blame for the Apple Watch launch screwups

It's been clear for a while that the Apple Watch launch had problems, with a lack of availability both online and in stores, and confused customers marring otherwise excellent sales.

But now, thanks to a report in the Wall Street Journal, we know what caused the issue - a serious technical fault with a key component from one of Apple's suppliers.

This suggests that Apple retail chief Angela Ahrendts was not to blame for launching the products even though Apple's stores had none to sell.

For days, Apple fans have been questioning the company's peculiar launch strategy. Why did it offer watches on April 24 when the company must have known there weren't going to be enough to go round? Why did she require customers to order the product online when Apple fans usually want to visit stores on launch day? Ahrendts all but admitted the launch was screwed up in a video after the April 10 online-order day.

But confusion arose even after the launch, when it emerged that the Apple Watch was not going to be actually in stock in any store for the foreseeable future. It was only available to buy online - but even those who did order it through Apple's website were told their orders could take weeks or even months to arrive. Meanwhile, Apple Store staff were overwhelmed with questions from confused customers, unable to understand why Apple's shiny new gadget wasn't actually available to buy anywhere.

We finally have answers as to how this happened - and it's not just demand outstripping supply.

It's not Ahrendts' fault, either.

Instead, it's down to a technical fault in the "Taptic engine" provided by AAC Technologies Holdings. The taptic engine is what provides vital feedback and notifications to the wearable through vibrations - but AAC's components have been found to be defective, breaking down over time.

AAC has now been dropped - and Apple's other taptic engine supplier, Nidec Corp., has been forced to take on the full load of production. But it isn't able to ramp up its output immediately, causing delays in the supply chain. These delays translated into a lack of stock, producing the subsequent problems we've seen.

As such, it's not a failure on the retail side, despite the frustration it is causing Apple Store employees. When retail chief Angela Ahrendts told Apple Store employees that the company had made the "hard decision" not to have the device available for purchase in store, it wasn't because Apple had misjudged the demand. It's because AAC Technologies didn't satisfy Apple.

It's not clear whether Apple will ditch AAC entirely as a result of the issue, but the company is feeling the pain. The Hong Kong company's stock has already dropped 8%.