Which idiom means "Pursuing a mistaken or misguided course"?

The idiom "barking up the wrong tree" means pursuing a mistaken or misguided course.

In contrast, the other options:
"Jumping on the bandwagon" means joining a popular trend or activity without careful consideration, which is different from pursuing a mistaken course.
Example- Everyone started juicing in the office, so I decided to jump on the bandwagon and bought myself a juicer too.

"Letting the cat out of the bag" means revealing a secret, which is unrelated to pursuing a mistaken course.
Example- I accidentally let the cat out of the bag when I told Sarah about the surprise party we were planning for her birthday.

"Spilling the beans" means revealing confidential or secret information, which is also unrelated to pursuing a mistaken course.
Example- I wasn't supposed to tell anyone, but I ended up spilling the beans about the new project our company is working on during the meeting.

Source: Cambridge dictionary.