Time Machine (Encrypted) Not Auto-Mounting on Boot with 10.14.4

After updating to 10.14.5 last night, my 8TB WD Time Machine drive won't mount. Can't repair, erase, etc.

Never had the issue prior, but it either it is a terrible coincidence or the issue isn't fixed.

Any help would be greatly appreciated.

iMac (Retina 5k, 27-inch, 2017)

3.8 GHz Intel Core i5, 40 GB 2400 MHz DDR4

Radeon Pro 580 8 GB

If your Time Machine still will not mount after 10.14.5 , and you cannot mount it manually with disk utility , or start it by selecting disk in system preferences : then either disconnect and reconnect it and try again ; or maybe you should erase and reinstall 10.14.5 over a clean HD disk , and try again ,to see if the time machine then auto-mounts , or even manually mounts .

@Seydlitz, I was having this issue up through 10.14.4 but 10.14.5 fixed it. It was totally a MacOS issue.

but - when the drive would not mount automatically, I was able to manually mount my drive and run Disk Utility diagnostics.

your problem sounds like a defective hard drive or USB port.

See if you can mount it on a different (mac) computer.

Hi everyone

I am absolutely desperate for help but have very limited technical knowledge!

My iMac suddenly started unmounting my three external hard drives. I am a photographer and have all my livelihood on these things.

I contacted apple and they said they can't imagine what the problem is but I will have to reformat my discs.

I have had a similar problem occur on my MacBook Pro with one of my hard drives - the Sandisk extreme SSD.

But after the problem occurred first, I had a futile conversation with apple and then I noticed that they suddenly mounted and so I ran a disk utility first aid on the two that came up.

I have recently bought these hard drives and used two of them before my iMac was wiped, because it has never worked properly, and one of them, since it was wiped.

The newly set up iMac was updated to Mojave 10.14.5 and the MacBook Pro is on the same system.

Apple have now told me to start my iMac up in safe mode and when the hard drives show up, run first aid and then move all the information across to one, reformat each in turn, and then put the stuff all back on.

However, after starting the iMac up in safe mode, predictably, neither hard drive will show up.

If I go into disk utility, they are pale and show as unmounted. When I ask to mount them, I get no response.

I did try and run first aid on one of them and it did allow it to happen but left it unmounted.

I am an extremely stressed lady now and just don't know how to move forward :(

Are all your external drives SSD's? SSD cases are likely unpowered. I own a couple of 4TB HDDs that are unpowered. Are you external drives self-powered (in a case that has its own power supply)? Have you tried booting up you iMac in safe mode with ONLY one of your external hard drives, and only enough external devices (like mouse pad if the iMac keyboard doesn't have one)? Unpowered devices plugged into your iMac draws power from the port it's plugged in. Too many devices drawing from the USB Controller in your iMac can prevent your drive from working properly with your iMac.

cmoy1 has very good points, also check your cables. I was having similar issues with an external drive, so I tried a new cable and the issues disappeared. consider purchasing a USB 'sled' which provides power and data connectivity. also try to mount the drives on a completely different system. if you keep trying too to mount these problematic drives on a problematic system you could corrupt the directory data and render accessible data inaccessible.

I had the same issue like you. So I found the solution for this, just add UUID to automount, follow this post https://discussions.apple.com/docs/DOC-7942

Hope it can help you, at this version.

This (https://discussions.apple.com/thread/250260889?answerId=250583127022#250583127022) resolved the issue for me. Thanks!!

Same here, used to auto-mount fine before the update. I have my password saved in the keychain so when I mount it manually from the disk utility, it doesn't prompt me for a password.

No issues here. I have an external USB (spinning) drive which is HFS+ formatted and encrypted. The drive auto-mounts and behaves as expected on my iMac running 10.14.4.

In my case, "Put hard disks to sleep when possible" is checked in Energy Saver.

My external USB drive is not configured as a Time Machine backup volume. It's just an external disk formatted as "Mac OS Extended (Journaled, Enyrypted)".

"it was flagged as duplicate within a few years"

I meant hours, not years ! Sorry.

No, it's not just specific to encrypted Time Machine-Drives. All Drives that are encrypted are affected, at least on my machine.

Does not work in my case.