Seagate External HDD won't show up.

Hence the reason why I strongly recommend against using disks formatted as NTFS on a Mac. The third party software vendors are always dragging their feet when it comes to upgrades. My recommendation is to only used NTFS formatted disks if no other solution can be found at all.

True... I agree with you, especially after the countless hours lost trying to figure this out. 🙂

On top of all of that there are applications that fail to function properly even with a functional third party software to enable writing to NTFS disks.

THIS FIXED IT HALLELUJAH. My hard drive was showing up just fine on the system report and showed on disk utility but said that the 1tb was completely full and it wasn't mounted. This silly issue was the reason why! I think maybe it was reset with OS Sierra or something because I hadn't had this problem before. Thank you!

Hopefully I'm replying to this thread correctly - having all the same issues with no luck. My computer ran the software update with the same hard drive (Seagate) plugged in and now it won't recognize it, on any mac.

Tried the Paragon NTFS drive panel suggestion and no luck. It does not appear in the disk utility but the systems report shows it on the USB...attached screen shot below. Is the hard drive just bad??

Thank you so much! This fixed my problem!

This worked! Thank you!

I went to System Preferences -> Paragon NTFS Drivers panel and ticked the box "Turn the Paragon NTFS for Mac OS driver off". My Seagate magically reappeared

I finally solved this problem (at least my version of it). My Seagate Backup Plus external drive would not mount to any Mac (I didn't test with a Windows machine). I finally realized that the Seagate Backup Plus drives have a removable IO interface on the bottom. If you grab the bottom portion of the enclosure and pull, you can remove that IO component. Since I have 2 other Seagate Backup Plus drives that both work, I swapped out the IO cartridge and BINGO. The drive that wouldn't mount finally mounted. I tried the IO cartridge on one of my known good drives and it would not mount. So this was a hardware failure of the removable IO cartridge.

**As a side note, these IO cartridges are interchangeable. I have 2 that are USB 3.0 (including the failed one) and one that is Firewire 800. I was able to mix the drives with both the USB and Firewire IO cartridges reliably.

Does this erase all contents on the hard drive??? Having the same issue but don't want to lose what is stored on there.

Fantastic!!! This works a treat. Hopefully the Paragon NTFS thing isn't important :O

You're very welcome! Glad it helped you out!

Same here. I also can only copy from my drive and cannot write to it. When I eject and reconnect I have same problem, and repeat.

Many, many thanks, killing the fsck_hfs process in Activity Monitor did the trick and immediately mounted the drive so I could copy the data to another drive !!

Go To "Finder Preferences"..... Sidebar..... Scroll Down to Devices. Click check box for Your Computers Name. That Should do it.

the same thing happened to me, did you ever find a fix for this?