Personally, I doubt the switch from Mate to Gnome is related.
There was a discussion about the "splicing" error here a few days ago, in this thread:
I have had that error particularly with large files. I've never pinned down if it is a buffering problem, or just that a huge file is more likely to evidence a random error.
My guess is your backup had file errors in it. Was it a plain backup? Or in a format with checksum/restore capabilities like .tar or even .zip?