It all started when the host said that Demi's show was "very obviously live," implying that it was not a good performance.
Well, the pop star responded, LOL-ing over the fact that Kathy is still following her career. (They got into a heated Twitter feud last year.)
The comedian followed back with a throwback photo of them together.
After last spring, we thought that everything was cool between them, but it seems like they're still not on the best of terms. Unless this is all just another big joke?!
Are you surprised that Demi and Kathy got into a fight on Twitter? Let us know in the comments!