Cannot Install Big Sur on Macintosh HD: What You Need to Know

When it comes to installing macOS Big Sur on a Mac, many users encounter issues with their existing HFS+ formatted drives. One of the biggest concerns is that converting an HFS+ Time Machine volume to APFS will erase all data, including Time Machine backups.

However, this is not the only challenge. If you want to shift a drive from HFS+ to APFS, you will need to reformat the drive. This means setting up a new drive from scratch with HFS+ to create new Time Machine volumes. The reason for this is that there is no way to convert an HFS+ Time Machine volume to one that uses APFS without erasing it.

Before formatting a Time Machine drive to APFS, it's essential to note that your old HFS+ based Time Machine volumes remain valid and readable in Big Sur. Existing HFS volumes will not be visible after updating, so it's crucial not to update any such volumes.

With macOS Big Sur, you'll need a drive formatted with Apple File System (APFS) to use Time Machine for backing up your files. If you're using an older Mac that uses Fusion Drives or regular hard disk drives (HDDs), be aware that they will not be converted.

Apple has promised APFS support for Fusion Drives, but as of yet, this hasn't happened. If you install APFS on a Mac with a solid-state drive (SSD) as the built-in boot drive, it will automatically convert to APFS without giving you a choice.

On the other hand, if you're using an older Mac that uses a Fusion Drive or HDD, you won't be able to opt-out of the transition to APFS. When installing macOS High Sierra and later on a built-in SSD, the drive is automatically converted to APFS.

APFS offers several advantages, including strong encryption, space sharing, snapshots, fast directory sizing, and improved file system fundamentals. These features will likely remain in future versions of macOS, such as macOS Monterey.

In summary, if you're experiencing issues with installing Big Sur on your Macintosh HD, it's essential to understand the implications of converting HFS+ drives to APFS. Make sure to backup your data regularly and consider setting up a new drive from scratch with HFS+ to create new Time Machine volumes.

Cannot install big sur on macintosh hd