Big Sur installation failure on an iMac

For everybody having trouble with the update, try these steps:

1. Restart the Mac, by pressing and holding the power button until the screen goes off, then turn it back on. See if the update completes within 2 hours.
2. If the update still does not work, shut off the Mac, turn it back on, but immediately press and hold the "Shift" Key on the keyboard. Release it when you see an Apple logo or globe on the screen. See if the update completes within 2 hours.
3. If the update still does not complete, shut off the iMac once again, turn it on, and immediately press and hold "Option" + "Command" + "R". Release when you see a spinning globe. From this new screen, connect to WiFi in the top right corner, and select "Reinstall macOS". (This will not erase anything, but you should have a backup.) See if the update completes within 2 hours.

Let me/us know if it still does not work.

Cheers,

Jack

Make sure you have a minimum of 50 GB of free space on your boot drive. Otherwise you may fall victim to this: PSA: Upgrading a Mac to macOS Big Sur without enough space can result in data loss

What did I do in the case that I updated with just enough space on my MacBook? The update is stuck on this screen and I can't access anything on my computer. It's just a loop of this

We had the hardest time getting it to download too and was downloading all night when my husband checked it this morning it had this pop up and we can’t do anything with it nothing is responding

Hi KAYNS,

What is the exact error you are seeing?

Cheers,

Jack

I receive a timeout error every time I try to upgrade.

My installation failed too - It is stuck at 1 minute left and will not work at all now - Can you help me?