I have had an external OWC Thunderbay 4-bay system for years, and it really works great on all of my Intel Macs. But when I connected it to my new Mac, MacBook Pro M1, it refused to mount, and I have no idea why this happened.
If you are now facing the Sonoma won't mount external drives error, you can first try fixing it in the following two methods:
Check if your external hard drive is mountable in desktop:
Fix your unmountable external hard drive with Terminal:
Once finished, type in type in diskutil eject disk_ to remove your eternal drive.
If you have lost your data during your update or the process to fix your eternal drive not mousting. Use EaseUS Data Recovery Wizard for Mac to help. This software can smoothly and perfectly recover lost files with a few clicks. It can recover data from formatted external hard drives on Mac and regain your precious memory.
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