Sidetrack (verb)

1. To cause to deviate from a course or direction.
2. To divert attention away from a main topic or issue.

Origin:

From side ("on the side") +‎ track ("path, rout.e")

Examples:

1. The discussion was sidetracked by an unrelated argument.
2. The meeting was sidetracked by a minor issue.
3. The conversation was sidetracked by a personal anecdote.
4. The plan was sidetracked by unforeseen obstacles.
5. The project was sidetracked by lack of funding.