Power Outage whilst installing Big Sur

[Laurie McCall]

My iMac was mid way through installing the new Big Sur OS update when there was a power cut/outage across our whole town. Now when I turn the Mac on I see this screen (see image attached). What should I do now? Any help would be appreciated! Thanks

 

[MacInWin]

About all you can do is to reinstall from the Internet. It's called Internet Recovery and is described in this: https://support.apple.com/en-us/HT201314

 

[Laurie McCall]

About all you can do is to reinstall from the Internet. It's called Internet Recovery and is described in this: https://support.apple.com/en-us/HT201314

Thanks, I'll try that.

 

[chscag]

Welcome to our forums Laurie.

Some advice: Buy an uninterruptible power supply and attach your Mac to it. That will protect you from power outages and give you a chance to shut the machine down properly.

UPS= Uninterruptible Power Supply

The Best Uninterruptible Power Supply (UPS)

We tested leading UPS models and found that the CyberPower CP900AVR is the best option to keep essential gear running for up to four hours during a blackout.

www.nytimes.com

 

[Laurie McCall]

Welcome to our forums Laurie.

Some advice: Buy an uninterruptible power supply and attach your Mac to it. That will protect you from power outages and give you a chance to shut the machine down properly.

UPS= Uninterruptible Power Supply

The Best Uninterruptible Power Supply (UPS)

We tested leading UPS models and found that the CyberPower CP900AVR is the best option to keep essential gear running for up to four hours during a blackout.

www.nytimes.com

Thanks, That sounds like a good idea. I've had a number of power cuts recently.

 

[Laurie McCall]

About all you can do is to reinstall from the Internet. It's called Internet Recovery and is described in this: https://support.apple.com/en-us/HT201314

Will I lose all of my data if I do this?

 

[Laurie McCall]

Will I lose all of my data if I do this?

I rebooted my Mac holding Command + R and am now reinstalling Big Sur. Thanks for your help

 

[MacInWin]

Will I lose all of my data if I do this?

You probably already have with the aborted installation, but it depends on how you choose to do the install. If you format the drive, then yes, everything will be erased. If you install OVER the existing system, and if it wasn't damaged in the power interruption, you might still have the data. Do you have any backup?