"attempting to write to non existent drive" copying large file to HDD dock

running on windows 10 pro x64, latest updates installed. v12.27 of dopus
i have a hdd dual bay dock , attempting to copy a single 3.2 TB container file from dock drive1 to dock drive 2 - error fails with "attempting to write to non existent drive". I am able to use windows file explorer without issue for the same copy.

The error comes from the operating system, so something must be going wrong outside of Opus, either in the OS, the filesystem or antivirus.

Did you check that Explorer can write the complete file? If the drive is limited to 2GB files then it may fail part-way through even though it looks like it's going to work initially, for example.

Do smaller files copy to the drive OK using Opus, or do all files fail to that drive?

Does the copy start in Opus or fail immediately? If it fails part-way through with that error then I suspect the drive, drivers, controller, or drive cable (etc.) are dropping out under sustained load.

I am about 25% through copy (launched from file explorer) of a 3.2TB file - will reply tomorrow with status.
Source and Destination drives are both formatted NTFS, so no size problem there.
smaller files copy properly
The copy of the 3.2TB file, when launched from dopus, fails after about 10 seconds of inactivity.

It might be worth trying a different drive cable, particularly if it's USB.

3.2tb file copied (started with windows explorer) successfully. i tried starting copy from dopus again, same problem. So, seems dopus related, unless you can suggest something else?

There have been a few things suggested to try already.

I changed cables to usb-c, same issue. what else is there to try at this point?

Do smaller files copy to the drive OK using Opus, or do all files fail to that drive?

smaller files copy properly

Could you make a Process Monitor log of what happens with the larger files? That should tell us which operation is failing:

I'm assuming copying the same file to an internal drive works OK (at least beyond the point it would fail on the dock drive) as well, but maybe that isn't the case?