macOS - Sandisk Professional, ArmourATD 4TB issues

WD External and Portable SSD External SSD for macOS
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Okay so this is the chain of events

  1. Purchase relatively new external hdd 2-3 years old max (Sandisk Professional, ArmourATD 4TB)

  2. Working perfectly

  3. Working fine on macOS Sonoma

  4. Upgrade to Seqouia

  5. Plug in HDD get absolutely nothing except one warning on the first plug-in that his hard drive can not be read etc

  6. Wait a few weeks for update then downgrade to Sonoma (downgrade using USB boot and wipe internal hard drive)

  7. Plug-in hdd and still does not work.

I have tried 3 different cables which work with other devices, the USB ports work with charger and other devices, it shows in system information but not in disk utility, the hard drive also has its light on and is spinning internally.

I just can’t remember what it is formatted in I believe possibly Mac OS Extended? I just really need the data from this hard drive its kind of important but also not worth spending thousands on if that’s the fee I will be charged. The only option I have left is to plug it into another mac computer or windows computer which I have not tried yet (this probably won’t work because its in mac format right?)

What do I do?

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If you google “external usb drive issue on sequoia” (or something similar) you’ll find quite a few hits.

If you have another Mac on Sonoma, backup your files before trying anything else.

Windows won’t read a mac drive but there are tools to help. You’ll see some of them in the result set. Whatever you do, DON’T FORMAT the drive until you’ve recovered your files.

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The thing is I have already downgraded and tried it on Sonoma and it still does not work, so I’m starting to think it’s the hard drive itself.