Apple has a disk image with the packaged Yosemite installer available from here: https://support.apple.com/en-us/HT210717
You could download that—of course, this means you’ll need a good Internet connection—and then build your external boot media from the app thus installed. Yosemite was a half-decent release, after a fairly rocky start, but out of curiosity, why? I mean, I only kept it for as long as I did because Apple broke El Capitan, Sierra and High Sierra in succession. I updated simply because I had to, and because Apple had introduced enough new functionality to justify it. You’ll never escape the bugs, whatever you do. IMO, but you might as well just use the latest and adapt. -- The following information is important for all members of the Mac Visionaries list. If you have any questions or concerns about the running of this list, or if you feel that a member's post is inappropriate, please contact the owners or moderators directly rather than posting on the list itself. Your Mac Visionaries list moderator is Mark Taylor. You can reach mark at: [email protected] and your owner is Cara Quinn - you can reach Cara at [email protected] The archives for this list can be searched at: http://www.mail-archive.com/[email protected]/ --- You received this message because you are subscribed to the Google Groups "MacVisionaries" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/macvisionaries/500129F9-D312-4694-B0A5-F6844D936FAD%40me.com.
