The best advice I can give to get around this is to follow one of these options:Ī fresh installation: Your old Mac might be a total mess of downloaded nonsense (I know mine is!): trials of applications you never use, libraries of samples that might become fashionable again in 20 years, that sort of thing. The reason for this is that the new Mac is looking for code that identifies the build of the machine, and this can happen even if the 'new' Mac has a system version older than the backup you are attempting to install. Attempting to boot from the backup drive is now met with the 'prohibited' warning sign that you describe. However, as you have discovered, this has now changed with Apple's most recent hardware releases. You could install a few updates, fix the disk permissions, copy the data and carry on as before.

You could then erase or partition the system disk on the new Mac and copy the old system across to the new disk. If your new Mac is already set up, Migration Assistant will copy across all applications, libraries, preferences and so on from the backup of your old Mac.Īs you suggest, common practice in the past has been to hold down the Option/Alt key and boot the new Mac from the old system on the backup drive. However, I first had an inkling that this may not be the way of things in future when the perennially donationware Carbon Copy Cloner app became a commercial concern (Mr Bombich has to pay his bills as well, I guess, but more likely was that some significant code rewrite was required). For quite a few years now, like you, I have also relied on the Carbon Copy Cloner utility to create a bootable copy of my system drive. SOS contributor Mike Watkinson replies: If your old Mac is heading south and is to be replaced by a brand-new model you may be forced to rethink the way you back up your hard drives.

Why is this, and how can I restore my old system to my new Mac? I have just bought a new Mac (a mid-2012 MacBook Pro) and hoped to repeat this process, but my attempt to boot from the backup drive was met with a 'prohibited' warning sign. The last time I bought a new Mac I simply connected the backup drive and booted from that by holding the Alt (Option) key, choosing the system, backing up, erasing the Mac's hard drive and copying the old system across using CCC. In order to back up my Mac, I used a backup utility (Carbon Copy Cloner), in addition to using Time Machine to create incremental backups.

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