Can you not sell land that someone is trying to claim adverse possion?

Yes, you can still sell land that someone is attempting to claim through adverse possession, but the sale may be complicated by the ongoing claim. The buyer may be hesitant to purchase the property if there's a risk of losing it due to the adverse possession claim. It's advisable to disclose any such claims during the sale process and possibly seek legal advice to address potential issues. Ultimately, the outcome will depend on the specific laws in your jurisdiction regarding adverse possession and property rights.