Clean install Yosemite

Do a backup before doing anything, preferable 2.

If you want to make a clean install of Mountain Lion, boot into the Recovery Volume (command - R) on a restart, use Disk Utility to Verify/Repair the disk and run Repair Permissions. Then erase the hard drive using Mac OS Extended (Journaled) format using the Options button. Reinstall Yosemite. Restart normally and test. Use Setup Assistant or Migration Assistant to import what you want.

Clean Install

You are welcome.

Yes, the clean install is the same for Mountain Lion and Yosemite. I meant to mention that, but obviously forgot. Setup Assistant/Migration Assistant will restore from Time Machine normally, barring an oops. I would use Setup Assistant as people seem to have better success with it. I recently did this on a computer in the house and had no problems. The restore from Time Machine takes awhile, so schedule it when you won't need the computer for a while.

You are welcome. I hope all goes smoothly for you.

I am planning to do a clean install of Yosemite and then restore from a Time Machine backup. I don't want to restore all the junk that has accumulated in the system over the years of upgrades. Is there a way to get my user data restored without copying all that junk back into the system folders? What options do I want to choose in the Migration Assistant to avoid the problem?

Migration Assistant

Migration Assistant (2)

Migration Assistant – Tips and Tricks

Hi Eric- Thanks for the reply. However, much of that information is out of date. From what I have read, the Yosemite Migration Assistant behaves somewhat differently than earlier ones in terms of accounts. But none of it addresses the details that I was after. If you have lots of accumulated junk in the System folder from apps that are no longer functional or from old installs of software that is functional, under some circumstances, Migration Assistant will put them back into the new System folder. The whole reason for the clean install is to get rid of that junk. What I was trying to find out is whether they come along when selects to restore Applications, or Other Files and Folders or somewhere else. Also there is the issue of the Library in the Home folder vs. the rest of the system. I have not found anything that explains the details of preventing restoring the junk.

If you intend to migrate an account clean it up for migration first, transferring apps and utilities that are not compatible with a new OS is a total waste of time at all stages.

Don't migrate your junk with your account.

Dear Csound1- I am not worried about the incompatible apps in the Application folders in the old setup. They simply won't work. It is all the stuff in the System, System Library and User Library folder I am trying to eliminate. It would be impossible to go through that and figure out what is needed and what is not. You would hope that the Migration Assistant would not put anything into those folders, but my experience is that it does.

So?

Identify them, then remove them, and don't make assumptions. Use etrecheck (post the report here) to help identify what is really running on your Mac, verify their compatibility, remove or update the ones that need it, then upgrade OS X.