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Boot Mojave from external SSD on iMAC with Big Sour

I sometimes like to use Mojave to still run Aperture. I have Mojave both on an external SSD and on a Partition of the internal SSD of an iMac where Big Sour is installed.

Whenever I use Mojave the return to Big Sour is complicated. Mojave before shutting down does not allow me to choose the other SSD for the next boot. The Mac doesn't boot right away. It goes into REcovery and takes a long time to restart. It forgets the trackpad connection. A lot of time is lost. Is there a better solution?

Can it be dangerous to use Mojave again this way ?

Should I install it under Parallels ?

Thanks

iMac 27″, macOS 10.12

Posted on Mar 21, 2021 10:31 AM

Top-ranking reply

WALTER-MILANO-ITALY Author

Level 4

2,250 points

Posted on Mar 22, 2021 12:03 AM

Running Big Sur from mi internal drive I open SYSTEM Preference and select the drive with Mojave (external or internal partition) to use it as boot drive to restart with. No problem to reboot and run Mojave. The way back is not easy because under Mojave Sys Pref does not allow to select a drive with Big Sure to restart.

I will follow your suggestion and not select Mojave drive from Big Sur but with option boot.

thanks

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Boot Mojave from external SSD on iMAC with Big Sour

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