Macbook Pro shipped with El Capitan won't work with Yosemite?

Well, the official company line has always been that you cannot install older OS software on a Mac than the version that it came with.

Having said this, I can tell you I have in fact install older versions of the OS on some computers, (Mac Pro towers). You will find very little in writing about whether you will be successful or not. I would make a backup of everything, partition the hard drive and try.

It has been my experience you can usually go back at least one OS version, but there are no guarantees.

Were you previously running Yosemite on an older machine?

I have no idea what you're trying to tell me.

If you have an older Mac running Yosemite, you can install Yosemite on an external drive and test whether or not your new Mac can boot from the external.

If you have a Thunderbolt to Firewire adapter, and if your old Mac can be put into Target disk mode, you could try booting from the old Mac when it's in Target disk mode.

I offered you a way that would allow you to test it for yourself. You're under no obligation to try it.

Ignore it then.

Bye.

Macs' build numbers/firmware changes continuously and which exact version they came with, so it depends exactly which build this Mac has - here is a list:

OS X versions and builds included with Mac computers - Apple Support

So, you can check which one yours is and see if yours may work with Yosemite.

I'd guess most likely not; however, if you have Yosemite on another Mac, I'd really try the suggestion to put a Yosemite install on an external hard drive, plug it into the Mac, and use the Option key at boot up (immediately after the startup sound) to get the Startup Manager - if the external shows up as a bootable source, boot from it to try it.

Only do any of this after you've made at least one (two are better) backups!

Another idea: if you still fall within the two week return period, return this one and take a look at the refurb section of the online Apple store. That is where I got my current iMac: I chose it because it could still run Mavericks which I need for my video editing software. So I put a Mavericks partition on the Mac and can boot into it if/when I need it. If you go that way, check on when the Mac was first released and ask them in a live chat about wanting to have whatever version you need installed.

Return machine and look around non-apple stores selling apple products... Best Buy etc.

1) Return machine and look around non-apple stores selling apple products... Best Buy etc.

online retailers are a great place to look. They often have excess inventory.

http://www.amazon.com/Apple-MacBook-MGXC2LL-15-4-Inch-Display/dp/B00G2MB7KW

http://www.macmall.com/s?rch&q=MacBook%20Pro%20yosemite&removedLicenseFilter=fal se&includeLicenseFilter=true&includeImage=true&ssrc=box

[ you best call to verify they still have yosemite. I tried to buy an older macmini online. I 'bought' machine but found later that my order was cancelled. ]

2) get the parallels app or Oracle Virtual box app and run the Yosemite in the resulting virtual machine. That is with this software, you can run Yosemite as an application in your El Cap machine. Warning, some apps may not work. Virtual box is free, so download and try.

R

I thought the SLA specified that you can only run the same OS version in VM that you already have running?