Getting baby in crib

Hey Moms. So since my son was about 3 weeks he would cosleep with me. I would let him fall asleep in my bed and then I'd move him to his playpen beside my bed. Once he turned 6 months I decided to start moving him to his crib in his room and it was going fine for a couple weeks and now all the sudden whenever I try to move him he wakes right up and starts crying until I bring him back to bed with me. Does anyone have any advice on how to get him to stay asleep in his crib? I think I created a habit for him 😩