Strange SDCopy Error
 

I was trying to move all my Time Machine backups from one external drive to another. Unfortunately, SD was getting snagged up. I have attached the log to this post.

Just to let you know I have resolved this via another piece of software (Carbon Copy Cloner) and no longer have a way to test. Even though the copy worked with CCC, Time Machine wanted nothing to do with itself and part of its source data being on new drives, so I just reformatted (thus I don't have the data to test with).

Any thoughts, though, on what would have caused this and what I can do to avoid it in the future?

That error generally means that the Time Machine "data" on the source volume is in a bad/incorrect configuration.