Apple is facing renewed criticism over an old problem called Error 53, which has been breaking phones repaired by third-party repair shops. A new story from The Guardian focuses on journalist Antonio Olmos, who broke his phone screen while covering the refugee crisis and was forced to have it repaired in a third-party store. Olmos' phone worked fine after the repair, but a subsequent update produced an "Error 53" screen. When he took the phone to an Apple store, staff told him the phone would have to be replaced out of pocket. The update had effectively broken his phone.

It's not the first time Error 53 has popped up, although the issue seems to cause the most problems after a new version of iOS has been pushed out. In April, The Daily Dot detailed similar issues and the same end result: once a phone met with Error 53, there was nothing to do but send it back to Apple HQ.

"Faulty screens or other invalid components that affect the touch ID sensor could cause the check to fail."

Apple acknowledged the issue in a statement to The Guardian, saying Error 53 was the result of security checks performed after installing an update, particularly the checks that pair the TouchID sensor to the internal Secure Enclave chip. Each iPhone maintains a unique pairing between the fingerprint reader and the internal chip, as a way of preventing fingerprint information from being extracted off the device.

"We take customer security very seriously and Error 53 is the result of security checks designed to protect our customers," Apple said in an official statement to The Verge. "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."

It's a tricky issue, particularly given how central the Secure Enclave is to the iPhone's overall security system. Without a verified connection between the TouchID reader and the Secure Enclave, the iPhone's fingerprint system could be vulnerable to any number of attacks, many of which have already been demonstrated on Android phones that lack a similar hardware verification system. Maintaining an internal verification system has kept TouchID protected from any such attacks, which in turn has enabled payment systems like Apple Pay to be built on top of the system. Without that verified connection, none of that would be possible.

At the same time, many of the reported issues seem to have nothing to do with TouchID at all. One typical case in Apple's support forums describes buying a phone in Dubai, repairing a simple screen crack at an unauthorized dealer, and only getting the dreaded Error 53 after upgrading to iOS 9 months later. Apple's explanation is that faulty screens may cause the check to fail. Still, the current system leaves the user with no way to recover from what seems like a common and predictable failure.

2/5 3:55PM: Updated to include Apple statement.