Cannot open pdf file on my 16tb USB drive but it opens fine on my 4tb and 1tb hard drives.

[Bob27309420i401]

I cannot open pdf files on my 16tb USB drive but they open fine on my 4tb and 1tb hard drives.  I have three drives attached to my notebook, and can open SOME small pdf files on my 16Tb USB connected drive but have no issue with my USB connected 4TB seagate external drive with the same files copied from the same locations on my C drive [1Tb internal hard drive] so what is the problem?

The file is obviously okay, since if copied from the 1Tb drive to the 4TB drive it opens fine, but will not open on the 16Tb drive. If I copy the working copy to the 16Tb drive it is reported as damaged, yet is fine in the 4Tb drive I copied it from and in the original 1Tb drive I copied it to the 4Tb drive from, so it doesn't make sense to me.  Is there something I need to do to the 16Tb drive before Acrobat will work in it?  One 18,000Kb PDF manual opens fine on the 16TB drive from a subdirectory folder and when copied from that subdirectory to the main directory also works fine, but larger files copied to the same drive fail all the time and it is frustrating.

[Test Screen Name]

Not sure from your description whether you have tried copying the file from the 16 TB disk back to the 4 TB disk a few times, and tried opening that new copy? What model is this 16 TB drive?

[Bob27309420i401]

I have no idea as it was obtained from Wish. It is 4 inches long, 1.25 inches wide and about 5/16th of an inch high, so it likely is made up of microchips.  I have tried copying from the 16Tb to the 4Tb and the 1Tb and they also do not work if they don't work on the 16Tb drive, but the same files work fine on the 1Tb and the 4Tb hard drives. The port on the 16Tb drive is a USB 'C' type connection.

[Bob27309420i401]

Launch

https://www.wish.com/search/16tb%20drive/product/6375d0c86c512be3c00a3a3b?

and this is what the 16Tb drive looks like. Mine is Red in color, so
click on 16Tb and Red and it will be shown on your screen.

[Test Screen Name]

Does it say "Portable SSD  - Mobile Storage" on the new disk? And did it cost closer to $3,000 or $100?

[Bob27309420i401]

With shipping it cost about $25 U.S. dollars

[Test Screen Name]

I've been doing some research, and I've been very surprised. From what you said, it seemed as if your disk was faulty. But it turns out, it is actually a fake disk! I've been reading that there are a lot of these. You can plug them in and they look good, but inside is just a tiny memory card and it throws almost everything away. Unbelievable! The price is the best clue. The lowest price for a 4TB SSD drive is around $300. That would make a 16TB drive around $1200, but they are so new, and hard to make that any real drive is $3000 and up. I know it's hard to believe there are factories somewhere set up to make fake disks and sell them, but there we are.  You don't have to buy from Wish; you'll find a lot of fake drives on Amazon. They sit there and keep selling, and keep getting 1 star reviews from people who say they don't work. 

[Bernd Alheit]

Have you checked the USB drive?

https://www.geckoandfly.com/22803/detect-fake-usb-flash-drives-sd-cards-ssd-disk/