After migrating to a new Mac, I found out that a ton of my web site passwords were gone or were out of date (I haven’t been using iCloud passwords or any other password app). The Migration Assistant seems to have problems under certain conditions. While I haven’t completely figured out the underlying issue, the only viable solutions were to either copy passwords to a new key chain or to use iCloud passwords temporarily or permanently.
On newer MacOSes password storage focuses on iCloud that is complemented with a local cache and local system passwords. You can find the password cache in key chain files and folders in ~/Library/Keychains. If you deactivate iCloud password use, the cache will be referred to as “Local Items” (if you decide to keep it). Every Mac gets its own UUID folder so if the migration succeeded you will find your old Mac’s folder and a new one for you new Mac. Now even with the files present on the drive the passwords were still missing. Copying those files around won’t help.
After investing a bit of time I decided to activate iCloud on my old Mac and then my on new Mac. The files are synced online and then to the new Mac (sure enough, during the experimentation phase this syncing deleted at least one of my very new passwords…). Since this did the trick, I am now even considering keeping iCloud passwords active and thus simplifying my future migration processes.
If you don’t want to store passwords on the iCloud servers permanently, just deactivate iCloud passwords on ALL devices (not that easy if you use a ton ;). Actually, Apple is suggesting that there is a way to completely skip password storage in the iCloud by not creating a Cloud Security Code. I haven’t tried this and am even unsure if this still works in Sierra.
