"The operation cannot be completed" error when copying files to external drive

William Barker wrote:

I am copying files from my SSD on my laptop to an external SSD, but I am constantly getting the message "The operation cannot be completed". the only hint as to what this means is an error code, which it turns out cannot really be researched (so what good is it?). I then have to go and figure out which files got copied and which ones did not, making this a VERY tedious process. What happened to the days when one could just copy massive folders from one place to the other, go to bed overnight and find everything done in morning? Any suggestions as to make this less tedious?

[Re-titled by Moderator]

Try a different external storage device and compare your results..