External drive doesn't show up on orignal mac it was created on, but does work on newer Mac.
Hi,
I had major problems with my i7 Imac internal, so I booted up with an external that I was using to start up with on my i5 Imac It was great and stable. I screen shared with it everyday for a few years, but it doesn't show up anymore on the i5. They are both running the same OS High Sierra. Could something have upgraded just being used on the newer Mac for it to not be recognized by the old Mac anymore?I don't remember clicking anything unless it was a security update maybe? It appears that it shows up in terminal before startup (Cmd-R. utilities), but I'm not sure if it's that disk. I see a 2nd disk that shows up in terminal on the old machine, but it's greyed out, so I can't run disk first aid on it. It also doesn't show up as an option to use as a startup disk.
Is it possible to fix it so that it will work on the i5 without erasing it?
Thanks,
Frank
iMac 27″ 5K, macOS 10.13