Apple’s macOS Tahoe 26.4 tightens security by binding the login Keychain to device-specific Secure Enclave keys, making manual copying of the login Keychain to another Mac unusable.

This change prevents users from copying the login Keychain from one Mac to another, a capability that existed in earlier macOS versions, and is confirmed to affect Macs equipped with Secure Enclave.

There are exceptions and workarounds: restoring backups to the same Mac remains unaffected, Migration Assistant is not impacted, but bulk corporate migrations may encounter issues, so users should export items beforehand or consider alternative password management options or iCloud Keychain.

For home users, iCloud Keychain offers a potential route to share passwords across devices and synchronize with iPhone and iPad as an alternative to manually copying the login Keychain.

The login Keychain is a SQLite database in the user’s home folder, and its decryption relies on a metadata key protected by the Secure Enclave, which must be accessed for the keychain to work on a new machine.

Testing showed that copying the login Keychain worked on macOS 26.3 and earlier and even in virtual machines, but fails on macOS 26.4 when opened on a different Mac lacking Secure Enclave access.

Apple’s 26.4 change, introduced with macOS Tahoe 26.4, was viewed by observers as a difficult-to-recover vulnerability that could strand users if a Mac dies or in emergencies.