A new 2020 iMac 27 inch with Catalina

[Zephar77]

I just received a new 2020 iMac 27 inch 512 SSD. Trying to transfer my boot drive from Late- 2014 iMac.
I have Carbon Copy Cloner Big Sur from my late – 2014 iMac to make a bootable external drive on a 1 TB SanDisk SSD, but get a message that states the 2020 iMac does not allow to use an external start up disk. Message states go into recovery mode choosing start up security utility. I did this selected start up security utility And put in the correct password and wouldn’t accept it. Before it would only let me install Catalina but now I’m installing Big Sur onto the SanDisk SDD, which already has Big Sur on it, but from a late – 2014 iMac, so I suspect there’s some differences that need to be added to that drive; but, I think I’m still going to have to use that start up security utility which puts the user name abbreviated, just my first name, and I put the correct password in and it just jiggles.
Anyone have an idea where I should go from here so I can erase the 512 SSD in this 2020 iMac and copy the contents of the SanDisk SDD with Big Sur on it and all my settings onto the new iMac?
Best, Seth

 

[Zephar77]

I just received a new 2020 iMac 27 inch 512 SSD. Trying to transfer my boot drive from Late- 2014 iMac.
I have Carbon Copy Cloner Big Sur from my late – 2014 iMac to make a bootable external drive on a 1 TB SanDisk SSD, but get a message that states the 2020 iMac does not allow to use an external start up disk. Message states go into recovery mode choosing start up security utility. I did this selected start up security utility And put in the correct password and wouldn’t accept it. Before it would only let me install Catalina but now I’m installing Big Sur onto the SanDisk SDD, which already has Big Sur on it, but from a late – 2014 iMac, so I suspect there’s some differences that need to be added to that drive; but, I think I’m still going to have to use that start up security utility which puts the user name abbreviated, just my first name, and I put the correct password in and it just jiggles.
Anyone have an idea where I should go from here so I can erase the 512 SSD in this 2020 iMac and copy the contents of the SanDisk SDD with Big Sur on it and all my settings onto the new iMac?
Best, Seth

I found a solution: The SanDisk connected to the 2014 iMac the user had selected account name which was just my first name, so that’s what showed up as a user with no other option when connected to the 2020 imac in recovery mode, for changing the settings for start up security utility; and of course the user needed to be my full name that the security utility wanted, but gave no option and filled it in with the abbreviated account name. Why? Why they would do something like that and make it impossible to make any changes without first taking the SanDisk back to the other computer clicking on the lock and system preferences/users and then selecting full name, then going back to the 2020 iMac and doing the process all over again -> This worked though. Proceeding with a strange start, Seth