Problem with latest update, please help

[RecentlyConverted]

Hi,

I run my Macs with external drives (rather than the internal), and backup to another external drive.

Since 2014, I have never had a problem updating the OS, even with this update, one iMac updated just fine. The second came up with the message "macOS could not be installed on your computer". It suggests going into diagnostics, but on powering on and holding D, it just tries to install the OS and fails again.

The computer is fine, as I changed the start up disk to internal, and that updated OK. I tried booting from my (CCC) back up drive, but when I tried to put the new OS update on that it failed too.

All very strange. Any ideas?

Thanks

 

[usagora]

Hi,

I run my Macs with external drives (rather than the internal), and backup to another external drive.

Since 2014, I have never had a problem updating the OS, even with this update, one iMac updated just fine. The second came up with the message "macOS could not be installed on your computer". It suggests going into diagnostics, but on powering on and holding D, it just tries to install the OS and fails again.

The computer is fine, as I changed the start up disk to internal, and that updated OK. I tried booting from my (CCC) back up drive, but when I tried to put the new OS update on that it failed too.

All very strange. Any ideas?

Thanks

Could you clone your internal drive to an external and see if it boots from that external ok afterwards?

 

[RecentlyConverted]

Could you clone your internal drive to an external and see if it boots from that external ok afterwards?

Hi,

I don´t have another drive here, so don´t want to wipe one to try (as I still need to get my data back and this way I get two attempts). Is there anyway I could add a partition to a drive, and back up to there, and then boot from there? I can´t find a way to boot from a specific partition, rather than a drive.

Its ok, I set it up and saw the partition as an option.

 

[usagora]

Hi,

I don´t have another drive here, so don´t want to wipe one to try (as I still need to get my data back and this way I get two attempts). Is there anyway I could add a partition to a drive, and back up to there, and then boot from there? I can´t find a way to boot from a specific partition, rather than a drive.

I thought each partition would show up as a separate selection under System Preferences > Startup Disk. Have you actually confirmed yourself that they don't? Not sure if one of these articles would help. If the drive you want to partition is formatted in APFS, then see the 2nd article.

Partition a physical disk in Disk Utility on Mac

In Disk Utility on your Mac, add, delete, erase, or enlarge a partition on a storage device.

support.apple.com

Add, delete, or erase APFS volumes in Disk Utility on Mac

In Disk Utility on Mac, add, delete, or erase APFS volumes.

support.apple.com

 

[RecentlyConverted]

I have booted up from the partition with the backup from the iMac internal HDD, and its running fine with the new version of Catalina. I just need to install it on my main partition.

The OS downloads ok, gets to 27 mins remaining, stays there for ages, then comes up with the error.

 

[RecentlyConverted]

Can I copy and paste the OS to the main partition, or wont that work?