At the moment on Big Sur, Safari claims to be running on 10.15.6, and Firefox claims to be 10.16. Chrome is the only major browser to correctly report 11.x, but it’s going to switch to 10.15.x too. I gather there were too many sites and Javascript libraries that incorrectly sniffed the User-Agent string, and couldn’t handle the change from. If your Mac isn't compatible with the latest macOS, you might still be able to upgrade to an earlier macOS, such as macOS Catalina, Mojave, High Sierra, Sierra, or El Capitan. 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.

Why can’t I downgrade from MacOS 10.15.6 to 10.14.6, in a 15inch retina MBPro 11,3 mid 2014, which was already running 10.11.6 originally when I bought it, and I upgraded to catalina. After installing about 75% of the setup of Mojave the installation stops and the message “unable to write firmware.” appears. The latest: Apple releases macOS Catalina 10.15.5 update Apple released an update for macOS Catalina that includes the new Battery Health Managment feature for MacBooks, and a new option to turn.

macOS Big Sur elevates the most advanced desktop operating system in the world to a new level of power and beauty. Experience Mac to the fullest with a refined new design. Enjoy the biggest Safari update ever. Discover new features for Maps and Messages. And get even more transparency around your privacy.

Update Mac Os To 10.15.4

Check compatibility

macOS Big Sur is compatible with these computers:

MacBook introduced in 2015 or later
MacBook Air introduced in 2013 or later
MacBook Pro introduced in late 2013 or later
Mac mini introduced in 2014 or later
iMac introduced in 2014 or later
iMac Pro
Mac Pro introduced in 2013 or later
View the complete list of compatible computers.

If upgrading from macOS Sierra or later, macOS Big Sur requires 35.5GB of available storage to upgrade. If upgrading from an earlier release, macOS Big Sur requires 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.

Make a backup

Before installing any upgrade, it’s a good idea to back up your Mac. Time Machine makes it simple, and other backup methods are also available. Learn how to back up your Mac.

Get connected

It takes time to download and install macOS, so make sure that you have a reliable Internet connection. If you're using a Mac notebook computer, plug it into AC power.

Download macOS Big Sur

If you're using macOS Mojave or later, get macOS Big Sur via Software Update: Choose Apple menu  > System Preferences, then click Software Update.

Or use this link to open the macOS Big Sur page on the App Store: Get macOS Big Sur. Then click the Get button or iCloud download icon.

Begin installation

After downloading, the installer opens automatically.

Click Continue and follow the onscreen instructions. You might find it easiest to begin installation in the evening so that it can complete overnight, if needed.

If the installer asks for permission to install a helper tool, enter the administrator name and password that you use to log in to your Mac, then click Add Helper.

Allow installation to complete

Please allow installation to complete without putting your Mac to sleep or closing its lid. Your Mac might restart, show a progress bar, or show a blank screen several times as it installs both macOS and related updates to your Mac firmware.

Stay up to date

After installing macOS Big Sur, you will be notified when updates to macOS Big Sur are available. You can also use Software Update to check for updates: Choose Apple menu  > System Preferences, then click Software Update.

Or get macOS Big Sur automatically

Update To Macos 10.15.2

If you're using OS X El Capitan v10.11.5 or later and your App Store preferences or Software Update preferences are set to download new updates when available, macOS Big Sur will download conveniently in the background, making it even easier to upgrade. A notification will inform you when macOS Big Sur is ready to be installed. Click Install to get started, or dismiss the notification to install later. When you're ready to install, just open the file named Install macOS Big Sur from your Applications folder.

Learn more

Upgrade To Macos 10.15.7

• If the installer shows a list of apps that are not optimized for your Mac, learn about 32-bit app compatibility, then choose whether to proceed with the installation.
• For the strongest security and latest features, upgrade to macOS Big Sur. If you have hardware or software that isn't compatible with Big Sur, you might be able to install an earlier macOS.
• You can also use macOS Recovery to reinstall the macOS you're using now, upgrade to the latest compatible macOS, or install the macOS that came with your Mac.