Updating to MacOS Big Sur

havara wrote:

• My iMac refuses to boot MacOS Big Sur. It is a 2017 iMac, so it is eligible for the update and I've got sufficient storage and system requirements. This is the process that happens very time I try:

successfully downloads Big Sur

• Big Sur installer application loads successfully and prompts me to restart

• the progress bar loads to about 5-10% of the way

• my computer restarts itself, then loads to the same point and repeats this over again

I have left it doing this restarting all night several times, and it has just carried on for upwards of 8 hours both times.

I have done what has been recommended by apple, even using time machine and completely resetting my computer (from which it managed to update to Catalina) but none of this has been successful for Big Sur. It is difficult to take a desktop computer to my local shop at the best of times, never mind during a pandemic. Does anybody have any other suggestions other than booking a genius bar appointment?

Verify you have available free storage—

Big Sur states that you will need 35.5 GB of free storage when upgrading from High Sierra or newer, and 44.5 GB when upgrading from an older versions.

After that reboot into SafeBoot mode and try again. SafeBoot https://support.apple.com/en-us/HT201262

just offhand. it sounds as if you downloaded a corrupt version of Big Sur. By any chance did you do the download via Wi-Fi? That often causes corruption and either the file can't complete the download, it won't install, or if it does, you get problems. I would try a clean new download using a wired Ethernet connection. See what happens then.

You might not want to update. Big Sur just bricked my imac