My mac has been installing Big Sur for over 24 hours now. It is a loading bar which finishes and then the screen goes black, followed by another loading bar. This has been repeating for a day. How do I fix this?
iMac 21.5″, macOS 10.15
Be sure you have a minimum of 35.5 GB of free space available for installing Big Sur. More, much more if possible - like 80+ GB which will also improve general overall performance.
If you current attempt isn't successful try the following:
1 - boot into Safe Mode according to Start up your Mac in safe mode - Apple Support .
NOTE: Safe Mode boot can take up to 10 minutes as it's doing the following;
• Verifies your startup disk and attempts to repair directory issues, if needed
• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)
• Prevents Startup Items and Login Items from opening automatically
• Disables user-installed fonts
• Deletes font caches, kernel cache, and other system cache files
2 - go to the App Store, search for Big Sur and download the full sized installer.
3 - run the installer from the Safe mode.
Be sure you have a minimum of 35.5 GB of free space available for installing Big Sur. More, much more if possible - like 80+ GB which will also improve general overall performance.
If you current attempt isn't successful try the following:
1 - boot into Safe Mode according to Start up your Mac in safe mode - Apple Support .
NOTE: Safe Mode boot can take up to 10 minutes as it's doing the following;
• Verifies your startup disk and attempts to repair directory issues, if needed
• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)
• Prevents Startup Items and Login Items from opening automatically
• Disables user-installed fonts
• Deletes font caches, kernel cache, and other system cache files
2 - go to the App Store, search for Big Sur and download the full sized installer.
3 - run the installer from the Safe mode.
As you know, there are two processes involved, the download and the installation. In my experience the download typically will take around an hour, more or less. Then the installation should go a bit faster. And there will be some restarts. I am guessing that your downloaded file may have gotten corrupted and is having trouble loading. This often happens when the download is done via Wi-Fi as it is too slow for these very large files. Better to use a wired Ethernet connection. If that is not possible, you may have to do several downloads to get a clean one that installs properly. The extensive time you are seeing tells me that something is not going well. I would go to a new download if this one has not yet installed.
It takes a long time and restarts often during the install.
I did mine overnight and it still took two hors more in the morning.
Big Sur won't install
