Sep 30, 2015 Install El Capitan. OK, now you can click that Continue button in the installer window. (If the installer isn’t running, go to your Applications folder and double click the Install OS X El. Then, you clicked on the folder now in here, select the image file of Mac OS X El Capitan and click on the “Open” button. Select Mac OS X El Capitan ISO file. Within this step, you’re finished with the settings. Now is the time to make a digital machine to Mac OS X El Capitan. Consequently, you have to press on Create. Download El Capitan. This will explain another way to install El Capitan to your device using external images file. DMG is a mountable disk image created for all Mac OS X versions and used to. El Capitan disk has an embbed security certificate that has expired in 2016. Just change your system date, let's say to, install El Capitan, then change the date back to today. MacBook Pro 15' Unibody Mid 2009.
To get the latest features and maintain the security, stability, compatibility and performance of your Mac, it's important to keep your software up to date. Apple recommends that you always use the latest macOS that is compatible with your Mac.
Find out how to upgrade to macOS Big Sur, the latest version of macOS.
The version of macOS that came with your Mac is the earliest version it can use. For example, if your Mac came with macOS Big Sur, it will not accept installation of macOS Catalina or earlier.
If a macOS can't be used on your Mac, the App Store or installer will let you know. For example, it may say that it's not compatible with this device or it's too old to be opened on this version of macOS. To confirm compatibility before downloading, check the minimum hardware requirements:
Safari uses these links to find the old installers in the App Store. After being downloaded from the App Store, the installer will open automatically.
Safari will download the following older installers as a disk image named InstallOS.dmg or InstallMacOSX.dmg. Open the disk image, then open the .pkg installer inside the disk image. It will install an app named Install [Version Name]. Open that app from your Applications folder to start installing the operating system.