Not recognizing external hard drive

Finally solved mine. Hope this helps! This is assuming your HD shows up in Disk Utility but not in finder.

1. Go to Disk Utility

2. Click your drive (in my case it was "Seagate Portable Media" with "Untitled" underneath)

3. Click Untitled - the "mount" button should work now/not gray anymore

4. Click mount

Your seagate HD should now show up in Finder. This happens to me from time to time and I'm really sick of downloading and reinstalling Paragon for GoFlex, and just unplugging and plugging for my older Seagate HD.

Additional info: Macbook Pro Retina 15" 2013

I am having the same problem as many that I have read above. Updated to El Capitan (10.11.2) and now my iOmega external hard drive isn't recognized. It does not appear in Disk Utility, Finder, Time Machine, etc. Have tried both USB ports on my MacBook Pro (mid-2009). Any other suggestions? Do I need to revert back Yosemite? Any help is MUCH appreciated!

I'm ultimately trying to transfer all of my files/iTunes/etc to a new computer, but can't back it up until the problem above is resolved.

Hi,

First time posting, and just wanted to share my experience.

I have a brand new MacBook Pro 13" 2015 with Retina display, less than a week old. My old Macbook Pro was backed up on a 1TB Seagate Free Agent GoFlex (FireWire, for Mac). I've successfully accessed the external hard drive multiple times on the new computer. However, when I plugged it in today, the computer wouldn't read the hard drive - nothing happened. I waited for a minute or two and then unplugged it and tried again - same problem. I tried rebooting the computer with the hard drive plugged in, without it plugged in, I tried accessing the hard drive in Disk Utility - all unsuccessful. I even tried reading it on my husband's MacBook Air and it STILL wouldn't read. I figured it was a problem with the hard drive and I'd have to throw it out.

Then I read this forum, and saw a few posts suggesting that it might just take some time for the computer to read the hard drive. So I tried plugging in the hard drive one last time, waited for about five minutes...

And then it popped up on my desktop! Success - the computer read the external hard drive!

Moral of the story:

1) This thread is awesome - thank you guys!

2) Have patience, young padawan.

- Miranda

Hey guys,

Ask something, why my external hard drive cannot be detected if i plug in after i start the macbook ? I need to restart the macbook then the external hard drive will be detected. Any solution other than restart my macbook ?

Thank in advance.

Make sure the drive has a GUID partition map, is formatted HFS+, test the file and volume structure and be aware that the vast majority of USB hub chipsets can only handle three drives and that's only if they have sufficient power.

I've found that some drives are power pigs and can cause recognition problems. A tool like this can be a fantastic troubleshooting tool.

This is a long shot but maybe somebody can give some insight.

Basically I have an older WD passport 1 TB external hard drive. I'm running El Capitan on a 2015 MBP. When plugged in it only shows up in System Information and not Disk Utility. It's running and spinning and not making any clicking noises.

So far I've tried:

Another MBP, same issue.

USB powered hub to see if it's a power issue.

Changed the USB connecting cord.

Nothing has worked so far. I will update on further research. Right now I'm just going to leave it in for a few hours and see if it can be recognized...

I am having the same problem, used to properly back up up every 2 months and did not back up for 6 months and tried a back up yesterday, meanwhile my os was updated to OS X 10.9.5 in this last 6 months. It seems something got changed on "Time machine" . I see my external HDD in Disk utility but Finder or Time machine does not see that. Also Disk utility could not unmount or do format new of my external HDD, It is all stuck now. APPLE ******** did not properly validate the OS X and all its component apps (Like Time Machine, Finder, Disk utility etc etc... something missing). I am going to ditch using Apple ******** products soon.

Hey everyone,

I'm having the same problem, but when I go to disk utilities mine shows up lets me run repair, after I run disk repair I get an error... Any idea what to do? I have a ton of important things on it.

I swear by Disk Warrior and Scannerz, but multiple backups make them less necessary than they used to be.

Unfortunately, a lot of people don't back up. In fact, it usually doesn't become SOP until after a disaster. Even then, they typically have just one backup drive, so your tools may still be use.

This fixed my issue!, my seagate 1Tb passport worked one day and didn't the next.

My drive showed up on all 3 of our PC's but nothing when plugged into my mac?

This linked worked a treat. http://www.seagate.com/support/external-hard-drives/portable-hard-drives/goflex/ ntfs-driver-for-mac-os-master-dl/

Thanks angelaknew

my Ex HDD stopped being recognised by MacBookAir suddenly. Anyone knows how to fix it?

I have been with Apple since 1994 and I used to have to unplug all the cables from my computer and any outside devices (we use to call them peripherals)

Funny how that still works today. I used your method of unplugging my backup drive in the order you said. Voila! It worked. Thanks,

I was having the same issue and was able to resolve it pretty easily. I disconnected the external drive form my Mac, opened Time Machine and deleted the back up drive. Then told it to set a new back up drive, reconnected the drive to the Mac and it recognized it just fine. However I can't right click on the icon for the drive to tell it to back up like I used to. I had to add the Time Machine icon to my menu bar and I can right click that to start a back up.

Hi,
Try to plug the external cable to your Mac and wait about good 20-30 minutes. If you check in terminal by typing "diskutil list", you will see your hard disk listed. It takes some time for the OS to process and show the hard disk. Just be patient.