Sep 30, 2015 Some apps are not compatible with EL Capitan and to avoid potential problems, you should check each app and see if there is a newer version. For Mac Store apps, open the Store app and select the Update tab. Install any updates you may find. For apps downloaded from the web, go to the app developer's website and check for updates.
I know that in the past if I've previously downloaded OS X El Capitan from the App Store I could download it again from the Purchased tab in the App Store, however now that macOS Sierra is out I'm not able to download it as it says INSTALLED (and grayed out) even on a system running OS X Mountain Lion 10.8.5. Pressing any key combination, e.g control, option, etc. doesn't change the button to DOWNLOAD. All other previous versions of OS X can still be downloaded from my Purchased tab in App Store as they still say DOWNLOAD and are not grayed out, thus active.
- Go to the App Store and open the El Capitan page there. Then you must click on the ‘Download; button on the El Capitan Page. If your Mac PC is compatible to perform this upgrade, a file named ‘Install OS X El Capitan’ will download to your Applications folder. The installer will open automatically after finishing the download process.
- Go to the App Store and open the El Capitan page there. Then you must click on the ‘Download; button on the El Capitan Page. If your Mac PC is compatible to perform this upgrade, a file named ‘Install OS X El Capitan’ will download to your Applications folder. The installer will open automatically after finishing the download process.
- Download OS X El Capitan. All Mac users who wish to download OS X El Capitan must do so from the Mac App Store, where it is available as a free download from Apple: Get the final version of OS X El Capitan from the App store here; The El Capitan installer is about 6GB in size.
Download El Capitan Without App Store
How Do I Download El Capitan From The App Store
The image below is from a system running OS X Mountain Lion 10.8.5, does not have OS X El Capitan installed on it or even the Install OS X El Capitan.app on its filesystem, yet it says it's installed and grayed out.