Q: Have migrated data every upgrade since OS9, should I perform a fresh install of El Capitan?

Me too.  OS9.2 and OS10.6 rule.  I'm still waiting for another decent system.

Anyway, about your questions.  I'm no code warrior but I think there are three approaches to an upgrade or move to a new machine:

Use the migration assistant.

Clone the original system and then apply the upgrade.

Start afresh and copy your data across.

Some have limitations depending on the vintage of the machine and the system.  I have tested all three and did not notice any difference. 

If you want a really fresh start use the last option, but you will have to set up all your tool bar preferences and there will be a thousand little annoyances for the first week.

I suggest that you stick with migration and then use something like Northern's Cache Cleaner App to clean the cobwebs:  http://www.northernsoftworks.com/elcapitancachecleaner.html

There is also Onyx but I have not tested it, but others on this forum (before it became deserted) used to favour it.

I wonder where everybody went?  Its been a while since I was here.

It is possible, but as soon as you start restoring/migrating your data/backups, you will be reintroducing older files.

To be most effective, you would need to erase the hard drive, install the OS, and then reinstall all 3rd party applications. When you restore your data, only copy the files you need.

Sorry for the 2nd post but I had to do something.

If you restore your user data, which includes your user Library, you would most likely be restoring older files.

On reflection, I agree with Eric.  I just checked my console log and there is a lot of bogus action during startup, although it does settle down after that.

A fresh installation is a bit of a pain.  There used to be a way that you could select which files to migrate.  If this still exists you could make a fresh installation, then migrate the Applications folder.  That way you would not have to reinstall all the software, especially if you can't lay your hands on the activations codes.  Once you are migrated, you can copy your data and then set up your system preferences the way you like them.

Eric, do you know if the selective migration options still exist and where to access them during the migration?

You are welcome. In an attempt to answer both of you, the best option is individually restoring of files from your backup; however, this is a long, tedious process. A clean install and using Setup Assistant is much quicker, but may restore some unneeded files. At some point you need to decide how much time you are willing to spend to get a completely clean hard drive.

I jumped from OS9.2 to 10.6 because I deemed the ones in between too buggy for my esoteric purposes.  I am now back on this forum because I am about to move from 10.6 to 10.11.6. 

Anyway, I migrated from 10.6 onto my current 10.11.6 test bed.  The console log shows pages of problems on start up.  I therefore want to echo Eric's advice that it WILL be better to do the fresh install.

The following is the alternative: it's what I will do but it will take longer than the fresh install.

Note the time on the computer clock and hit restart.

Wait five minutes and open the console.

Scroll back up the log to the restart time, which should be indicated.

Start reading the log and looking for processes that are glitching.

Then  you have to identify their source and delete it or reinstall the parent App.

All the while be careful not to delete anything that breaks the OS.

Good luck.

Hi Michael, Oxcart, et:all

IMHO everyone should do a complete fresh install with every major OS upgrade. There are particular OS upgrades that contain some fundamental underlying frameworks that change how MacOS works. Simply using Migration Assistant(MA) to migrate brings along lots of crud that you do not want or need. It is also possible that you are bringing along hidden security and operating vulnerabilities and problems. Doing a full "Fresh" install removes these problems. It also makes troubleshooting much easier.

Here's what I do.

Make a complete backup and a clone of current System (boot) drive.  Install the Back Ups and Clone on separate external hdds. If using a Mac that allows installing new or additional drives (like the legacy Mac Pro, I just install a fresh HDD).

Erase the boot drive. Install new OS clean. Do not use MA/Time Machine to transfer/restore user accounts, files, etc….

Create a new Admin account using a new password.(When was the last time you changed your login password?) You can still use your Apple IDs and app store accounts.

Reinstall all apps from App Store or discs clean. Update if necessary. You now have the latest versions with no crud.

Sometimes the crud contains hidden things that can cause problems like outdated fonts, plugins, extensions, etc….

You can use iCloud for contacts, etc…

Now you can connect your BU or clone drives and copy any files you need to your internal boot drive. Copy and paste or use drag and drop. Here is where you need to decide what you really need. Don't bother to copy any files that you don't use all the time, you can still access them at any time from the external drives, do that for most files(95% most likely). When you copy and install on your internal drive, all appropriate permissions will get applied and will loose any older permissions that are outdated and possibly contain security issues. Apple has updated the underlying UNIX code with updated ACLs that provide greater user protections.

Now you have a very clean system that will be fast, clean, secure and will make trouble shooting any problems soooo much easier. I do a lot of support work and see migrations issues more than I want too. I just do the above steps for the really problematic Macs and almost always the problems go away.

Yes, not nearly as easy as using Migration Assistant, but almost always trouble free.

For simple OS point updates, just back up first, then update, these are mostly bug fixes and security updates.

Back Up, Back Up, Back Up! The very most important tip I can give. I use both Time Machine and Carbon Copy Cloner for both Back Ups and Clones on at least 3 separate drives and update sequentially. Hope you do too!

Hope this helps, Greg