USB and external hard drive not recognized after updating to MacOS Catalina

I just lost my 2nd external hard drive since upgrading. I'm on a 2014 Macbook Pro. Lost a brand new Seagate 5 TB, now just lost a 4 TB I've used for years. They initially worked in Catalina, but now only appear in Disk Utility but refuse to mount.

I'm having the same issue. The last time this happened I downloaded the new update and my drive stopped showing up. After browsing online for hours trying to find a solution, I finally noticed there was another software update from apple and after downloading that, my drive started showing up again. I'm having the same issue again - I just got a brand new mac and no luck with my external hard drive. Did you resolve your issue? Would love to see if you figured it out.

Very basic fix that doesn't work. None of these "suggestions" make any difference, nor does using a powered USB hub: https://appletoolbox.com/mac-macbook-doesnt-recognize-external-drives-troubleshooting-tips/ Surely apple has a fix for this as it is frustrating and not the first time I've had this issue with a Mac (had on the last update of the previous operating system). I have search all of the forums and tried every solution suggested. It is clearly a software issue as my drives worked on my Mac previously and work without issue on a PC! My Mac is a MacBook Pro (13-inch, 2017, Four Thunderbolt 3 Ports) and is running Catalina 10.15.2. I have tries several drives of all brands as I own many. Will read small plug in USBs just not drives (even drives with own power supply).

USB drives won’t mount on desktop or show up in Disk Utility, UNLESS they are plugged in, powered on, and I reboot the computer. Then it will show up on desktop and disk utility. Then I can mount and unmount using disk utility, however if I eject and unplug USB cable and plug it back in, it will spin up but will not mount again until another reboot....

I updated 2 days ago and my hard drive or USB won't show. I know it's the Catalina update because I backed up all my files just before the update onto my hard drive. no problem.

The conversion USB thing that plugs into the thunderbolt lights up, my hard drive lights up and I can hear it come to life, but it can't be found anywhere. Not in disk utilities either.

I run my own business and need these files. I don't have the time to now spend hours looking to access my files!!!! this is a joke!!

i just purchased a mac book pro air on dec 2019 and the apple external disk drive; everything was running great until I did the catalina update, now my mac won’t recognize it, it reads my external hard drive no problem I tried everything on line any suggestions? Or will there be another update to fis the glitch?

I've tried every reboot listed and I've downloaded the Seagate Paragon Support, but to no avail my external hard drive is not being recognized by Catalina. Under System Report > USB I can see that it's physically plugged in, but it's not mounting.

Any other recommendations? I'm desperate.

The biggest mistake I’ve made was to update to Catalina OS from Mojave OS on my MacBook Pro 2019. I purchased an expensive docking station (Brydge Stone Pro) which is not fully functional with Catalina OS, in that certain of my flash drives plugged into the Stone Pro do not register on the Mac. I had to purchase another docking station (Caldigit) which works better with Catalina OS, but even then a DM flash drive plugged into the Caldigit doesn’t always show on the Mac when it boots up, unless I plug it in again. And another big frustration is that my audiophile DAP (Cayin N5ii) is not compatible with Catalina OS, whereas it worked perfectly on Mojave OS. Let’s hope that the macOS 11 Big Sur will be a better OS.

Hello

I tried this but it made no difference.

I had this problem when I bought my brand new very expensive Mac Book pro a few months ago, it came with Catalina and has been so full of issues, this being the most frustrating one!

I am a video and photo editor and so I cannot begin to describe the time and frustration this bug is causing me. I cannot upload files to clients, sites or transfers from my ext drive (WHERE EVERYTHING IS LOCATED). Everything has to first be dropped onto my desktop and then uploaded from there! The desktop which is now telling me that it is full, because it is not a normal desktop oh no, it is linked to iCloud and I don't know where the std old desktop option went!?

Another ploy from Mac I suppose to get you to upgrade the cloud space. Nice one. When did Mac stop making expensive but useful products and start making a monetised series of hurdles to force its consumers like rats into buying more unnecessary add ons and extras.

The simple work flow has been replaced by a barrage of headaches and owning this new Mac has been more of a hinderance than help!!

I can get one of my external HDDs to show up on-screen at a time, but not both. USB via Apple purchased adapter. Not both at once, but at least not neither at all.

I use paragon NTFS, and it can't see the external HDD after installing Catalina, and the HDD works on 2 others direct Windows PCs

Restart didn't work for me. I have a Pluscom external drive. It must be ten years old but, after all, it is for storing stuff.

Thanks, Sharmar7,

with joy I can report that the instructions on your link to RESET THE NVRAM !!!!WORKED!!!! For any readers who are as lost as me, the Options key is marked "alt" on many keyboards.

Same issue here.. : (

We bought such expensive computers, problems like that should never happen.

Reseting the Nvram didn't work for me.

Nothing worked actually.

I too am having this issue. I can't belive this is not something apple have resolved. It's such an obvious screw up.