macOS 26.4 silently enabled login keychain data protection

This is a follow-up to my September 10 blog post macOS Tahoe silently sabotaged the login keychain A subsequent addendum to the blog post noted that the change was introduced in a specific version of macOS Tahoe, 26.4, released by Apple on March 24. In brief, macOS 26.4 added a restriction to the login keychain that makes it non-portable, impossible to unlock outside of its original context. Consequently, recovery of login keychain data from backup has also become impossible in some critical circumstances, most notably if your Mac is lost or broken. Apple has sabotaged disaster recovery for Mac users, who may not discover the sabotage until it’s too late, after disaster occurs. Even Mac users who have tested their disaster recovery process will get caught unawares if their testing was done prior to the macOS 26.4 update. I believe I now understand what changed exactly in macOS 26.4: Apple enabled data protection for the login keychain, like on iOS. Some people who read my previous…