You may not install to this volume because the computer is missing a firmware partition.

You may not install to this volume because it is currently being encrypted.

The update cannot be installed on this computer.

If you have backed up your Mac to an external hard drive with Time Machine, you can simply restore from the Time Machine backups. Here is what you should do if you've encountered data loss after the macOS software update: Though Apple has made a precaution that important files may get lost if the macOS software update is interrupted, many of you still forgot to back up your MacBook Air/MacBook Pro/iMac/Mac mini. How to restore or recover lost files after macOS Big Sur update? If you are using third-party software to back up your Mac, check if it's ready for macOS 11.

Note that these backups and new backups created after are only compatible with Mac computers running Big Sur and later. In that case, your existing backups are also upgraded to be used on macOS Big Sur. Suppose you upgraded to macOS Big Sur on a Mac that uses a Time Capsule or other network storage device as the backup destination. Therefore, it's always recommended to back up Mac files before every major macOS software update using the built-in Time Machine. It makes data backup with third-party apps difficult, especially those that offer bootable backups.

Since macOS 10.15 Catalina, Apple split the startup disk into two separate volumes, Macintosh HD and Macintosh HD - Data. Built-in or Third-party Apps Issues in macOS Big Sur

Poor Performance When Using macOS Big Sur Startup issues after installing macOS Big Sur

Fail to download and install macOS Big Sur In the following sections, we will talk about practical solutions to fix macOS Big Sur problems.

Instal the new version for mac Frozen