The Guardian reports that Apple has acknowledged growing complaints that third-party repairs to the Touch ID home button of an iPhone 6 can brick the device when iOS is updated, and that it is a deliberate security feature.

There have been growing reports of an ‘error 53‘ following an iOS update to an iPhone 6, leaving the phone dead. A Guardian freelancer was one of those affected.

Freelance photographer and self-confessed Apple addict Antonio Olmos says this happened to his phone a few weeks ago after he upgraded his software. Olmos had previously had his handset repaired while on an assignment for the Guardian in Macedonia […]

He says he thought no more about it, until he was sent the standard notification by Apple inviting him to install the latest software. He accepted the upgrade, but within seconds the phone was displaying “error 53” and was, in effect, dead. When Olmos […] took it to an Apple store in London, staff told him there was nothing they could do, and that his phone was now junk … 

iFixit’s Kyle Wiens said that hits on the company’s website showed that a great many iPhone 6 owners had experienced the problem, and that there was no way to fix it.

The ‘error 53’ page on our website has had more than 183,000 hits, suggesting this is a big problem for Apple users. The problem occurs if the repairer changes the home button or the cable. Following the software upgrade the phone in effect checks to make sure it is still using the original components, and if it isn’t, it simply locks out the phone. There is no warning, and there’s no way that I know of to bring it back to life.

Apple has now confirmed to the Guardian that the issue exists and is caused by code designed to protect the Secure Enclave.

We protect fingerprint data using a secure enclave, which is uniquely paired to the Touch ID sensor. When iPhone is serviced by an authorised Apple service provider or Apple retail store for changes that affect the touch ID sensor, the pairing is re-validated. This check ensures the device and the iOS features related to touch ID remain secure. Without this unique pairing, a malicious touch ID sensor could be substituted, thereby gaining access to the secure enclave. When iOS detects that the pairing fails, touch ID, including Apple Pay, is disabled so the device remains secure.

The company did not go as far as acknowledging that there was no possible recovery once the issue has occurred, but simply advised affected users to contact Apple support. We have asked Apple whether it is able to restore or repair affected phones and will update if we get a response.

Update: Apple has issued a more detailed statement pointing those who need assistance to Apple Support:

In a statement released following the publication of the Guardian’s story, an Apple spokesperson said: “We take customer security very seriously and Error 53 is the result of security checks designed to protect our customers. iOS checks that the Touch ID sensor in your iPhone or iPad correctly matches your device’s other components.

“If iOS finds a mismatch, the check fails and Touch ID, including for Apple Pay use, is disabled. This security measure is necessary to protect your device and prevent a fraudulent Touch ID sensor from being used. If a customer encounters Error 53, we encourage them to contact Apple Support.”