You bought a CD, madness.

If you want to upgrade your Mac from Yosemite to another newer OS you have three alternatives..

If upgrading from macOS Sierra or later, your Mac needs 35.5GB of available storage to upgrade. If upgrading from an earlier release, your Mac needs up to 44.5GB of available storage. To upgrade from OS X Mountain Lion, first upgrade to OS X El Capitan, then upgrade to macOS Big Sur. Double-click the Mac OS X Update Combo package file (it looks like a little box or package) found on the mounted disk image. Click Continue and walk through the update installer as usual. Select the target hard drive for the Combo Update to be installed onto (typically the Macintosh HD startup disk) and click “Install”.

A list of OS X 10.11 El Capitan 'combo' updates OS X 10.11 Combo Updates For more information on the difference between normal and 'combo' updates including recommended instructions for installing updates see this article. OS X 10.11.6 Combo Update; OS X 10.11.5 Combo Update; OS X 10.11.4 Combo Update; OS X 10.11.3 Combo Update. 'Your OSX 10.11 El Capitan Is Infected With 3 Viruses!' Is just one of many scams of this type, and very similar to Your System Is Infected With 3 Viruses, This Mac Is Not Secure, Your MacOS 10.12 Sierra Is Infected With 3 Viruses, and a number of others.

El Capitan, Sierra and High Sierra are all available for download and are free.

It sounds like you have been trying to install updates to El Capitan downloaded from the Apple Support Downloads pages. If so you need to have already installed El Capitan, that is why you are getting the message about 10.11.

for example if you downloaded the 10.11.6 Combo update this will update any previous version of El Capitan from 10.11.0 to 10.11.5 to the last version 10.11.6. Please remember full versions of OS's are only available via the Mac App Store.

Depending on the age of your Mac you may not be able to upgrade to Sierra or High Sierra, if so you should be able to upgrade to El Capitan.

Have a look at the links below to determine what OS you would like to download. Bear in mind though that if your Mac qualifies for High Sierra then you will be denied the download of El Capitan.

The versions that will be downloaded in each case will be the latest versions of each OS, so for El Capitan it will be 10.11.6, Sierra will be 10.12.6 and High Sierra will be 10.13.3.

El Capitan 10.11.6 Update Problems

If you tried Erics link to El Capitan and you couldn't download it, then the App Store is recognising that you Mac qualifies for High Sierra, so you can upgrade to that or if you want you could also upgrade to Sierra from the link above.

Download Os X El Capitan 10.11.0 Combo Update

Feb 28, 2018 12:24 AM