Here are some tips: https://www.royalhomepainterstoronto.ca/fixing-peeling-paint-ceiling-repair-toronto/
Bubbling paint needs to be scrapped off, sanded down smooth first. If needed a coat of primer and then re paint the door.
Unfortunately, it sounds like you'll have to repaint. Perhaps the moisture from the bathroom is causing this.
Do you use an exhaust fan in your bathroom and is the paint bubbling on the inside or outside of bathroom door? I ask because if it is on the inside (the side facing the bathroom) it sounds like you have a moisture problem. Even if you sand the door and repaint if you don't fix that problem it will happen again.
I agree with this! Make sure you have a way for the moisture to escape and not build up. Then you will need to repaint the door. Sand it smooth first.
My question was peeling and bubbling paint on the ceiling. Has been repainted a million times with all kinds of paints that say prevent peeling and bubbling. Besides for good ventilation any ideas???