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Installation of MacOS Big Sur always stops at 'An error occurred loading the update'

I've tried several times to install MacOS Big Sur, but the installation always stops at that error message. Fortunately, my computer is still working, as I've heard some horror stories of computers crashing during installation.


Has anyone been able to fix this problem, and install Big Sur. If so, please let me know how you did it.


NB The update was self-downloaded by the OS, not from any third-party site.

Posted on Mar 2, 2021 7:08 PM

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Question marked as Top-ranking reply

Posted on Mar 3, 2021 4:31 AM

Suggest - restart Router and then Shutdown Computer and connect via Ethernet connection. Restart computer in Safe Mode - Shift - Key immediately at startup. It does a Repair Disk, clears cache files and load only Apple Software - load slowly - Normal. Once in Open Apple Apps Store and find Big Sur and download. Try not to let computer go to sleep mode or Screen Save to activate. Be patient as one knows it Big Sur is 12.18 GB size. There are often periods where it seems to pause the download , normal be patient as countdown clock may say 15 minutes but in Real Time could be 30 - 45 minutes. This can and will happen several time in the process. If all goes well. it will successfully download and attempt to Launch. Do NOT allow it to start - Quist the Installer. Check Applications Folder for new App called Install Bug Sur. Make a copy to External Drive - future usage. Now, restart again in Safe Mode - then launch the Installer.

3 replies
Question marked as Top-ranking reply

Mar 3, 2021 4:31 AM in response to Crocefisso

Suggest - restart Router and then Shutdown Computer and connect via Ethernet connection. Restart computer in Safe Mode - Shift - Key immediately at startup. It does a Repair Disk, clears cache files and load only Apple Software - load slowly - Normal. Once in Open Apple Apps Store and find Big Sur and download. Try not to let computer go to sleep mode or Screen Save to activate. Be patient as one knows it Big Sur is 12.18 GB size. There are often periods where it seems to pause the download , normal be patient as countdown clock may say 15 minutes but in Real Time could be 30 - 45 minutes. This can and will happen several time in the process. If all goes well. it will successfully download and attempt to Launch. Do NOT allow it to start - Quist the Installer. Check Applications Folder for new App called Install Bug Sur. Make a copy to External Drive - future usage. Now, restart again in Safe Mode - then launch the Installer.

Installation of MacOS Big Sur always stops at 'An error occurred loading the update'

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