I have installed Big sur beta in 1 partition with other Mojave OS partition. When I am in Big Sur, startup disk shows Mojave OS but in Mojave it doesn't list Big Sur so that I can switch OS from there only.
Big sur beta OS not listing in Startup Disk
Does the macOS 11 beta partition show up in the boot picker you get by holding down the Option key at boot?in Mojave it doesn't list Big Sur
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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
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I installed Beta Big Sur yesterday over beta Catalina. 12gb download! All went well. I was able to boot from external drive, but when i booted into Mojave on my 2014 iMac, a warning came up that the external drive partition was not compatible with Mojave. I clicked continue and Mojave mounted a partition that contained none of my data but had the same capacity of the Big Sur installation. I chalked it up to a new ‘flavor’ of APFS which is not visible to previous systems to Big Sur. Can someone clear this up for me?
yes. but not on Mojave startup disk menuDoes the macOS 11 beta partition show up in the boot picker you get by holding down the Option key at boot?
Hey Eskimo... kind of... I see a mysterious UEFI device that sometimes boots me back in Big Sur (sometimes I end up in recovery mode). The time I had to go back to Catalina (from Big Sur Beta 6, with the target disk swapping as if it was a card game of “where/find the Queen”... not joking :)) and back to Big Sur using the launch boot picker (had to do it twice, only disk the Safe Mode could see was the Big Sur - Data partition which I could not mount... did not accept my password either) ... I lost some user profile data (settings for iTerm and Firefox were gone, had to get them back/recreate them).
I have not formatted any drive/partition APFS for use with Mojave. I have two external HD 4TB drives and 3 1TB SSD. The internal is a 500GB SSD. The only partitions that have been formatted APFS are for Catalina and Big Sur. I have a mix of both on both of the external HD drives and one of the SSD.
If you have the luxury of accessing an external drive with partitions, reformat one partition to standard extended and backup your Mojave partition to that partition. If necessary, delete the / a APFS partition (if you have extra or duplicate) and reformat. Then, run the disk repair on each of the individual APFS components. If one fails repair, skip to the next, then return to the one that failed. Reboot into Mojave.
Cannot guarantee that this will solve your problem, but it solved mine. When in Big Sur, the icon of the drive to select appears; when in Catalina or Mojave, the small icon with drive name beneath appears. I have no problem selecting any drive to boot. And Mojave, limited to a single "home" loads properly.
If you have the luxury of accessing an external drive with partitions, reformat one partition to standard extended and backup your Mojave partition to that partition. If necessary, delete the / a APFS partition (if you have extra or duplicate) and reformat. Then, run the disk repair on each of the individual APFS components. If one fails repair, skip to the next, then return to the one that failed. Reboot into Mojave.
Cannot guarantee that this will solve your problem, but it solved mine. When in Big Sur, the icon of the drive to select appears; when in Catalina or Mojave, the small icon with drive name beneath appears. I have no problem selecting any drive to boot. And Mojave, limited to a single "home" loads properly.