When you save a card to your Wallet, like a pass for public transit, a card for Apple Pay, or the key for your car, it's saved to something Apple calls the Secure Enclave. It's where your iPhone saves all of the important things that need the utmost security and your cards fall into that category for obvious reasons. But while it's no surprise that the Secure Enclave has a finite amount of space in which to save things, you might not be aware that it's actually possible to reach the point where that space is full and the only way to fix that problem is to delete some cards.
What's more, the Wallet app will not allow you to add any more cards until after you make some space and that means that you might have to make some difficult decisions about which cards you need, and which you don't. I'd suggest keeping the card that unlocks your house or car and ditching the supermarket loyalty card, but the decision is yours.
While it's unlikely that most people are going to find themselves having to deal with this issue, it is an issue that some are seeing crop up. A post on the X social network was my first inkling that this was a thing and a search suggests that it's happened to other people in the past as well. Judging by the responses on the X post linked below, I wasn't the only one who didn't know that it was possible to get the Secure Enclave into such a position that you can't add any more cards. Now I do. And now, you know too.
Unable to add card
The situation came to my attention when the X account @TapDownUnder shared screenshots of the screens that Apple's iPhone displays when the Secure Enclave is full. Users see a chart similar to the iPhone storage chart found in the Settings app along with the message that the Secure Enclave on their iPhone is full. They're then instructed to check their usage and remove enough cards to free up more space.
You know you have too many cards when..... pic.twitter.com/2DYcEOckKzJanuary 24, 2024
Again, it's unlikely that most people are going to reach such a limit but it's clearly possible. There are other examples of the same behavior online as well, suggesting that it might be easier to find yourself falling foul of the Secure Enclave's limits than you might expect.
If you do find yourself in need of more space to add a new card to the Wallet app there's little you can do other than make space by removing others. And maybe figuring out how you managed to collect so many cards in the first place.
Apple's support documentation explains that "the Secure Enclave is a dedicated secure subsystem integrated into Apple systems on chip (SoCs)." It goes on to say that "the Secure Enclave is isolated from the main processor to provide an extra layer of security and is designed to keep sensitive user data secure even when the Application Processor kernel becomes compromised."
You'll find such a Secure Enclave in the iPhone 5s and newer as well as all modern iPads. Macs with Apple T1 and T2 security chips also have Secure Enclaves built in as do all Macs running Apple silicon. All Apple Watches, the HomePod and HomePod mini, and the Apple TV HD and later all also have a Secure Enclave to call their own.
