In Season 6 Episode 2 "Conspiracy" of Star Wars: The Clone Wars, as
he states that "the mission" and "the nightmares" are gone.
Similarly, in Season 6 Episode 3 "Fugitive" as
he states that the "mission" and "nightmares" are gone.
What are they talking about?
The only unique circumstances connecting these troopers that I can think of is that neither of them
had the Order 66 bio chip in their heads when they died.
That leads me to speculate that both the "mission" and the "nightmares" are related to it, though that doesn't give me any clues of what the "mission" and "nightmares" actually are.
Is there a canon explanation of what they are talking about? If not, are there any particularly popular fan theories of what they are talking about?