Hello @sharic Hearty Welcome to the Candy Friends section of our friendly King Community
I am sorry to hear about the issue in your game!! To move forward after beating level # 540, you will have to delete and reinstall the game which facilitates you to move ahead! I am not sure about the reason, but the game is designed like that only for this level. After this, the game works fine and no issues for us to go ahead in the game!!
But please aware that, you will be loosing all your saved up boosters (Lollipops) with deleting the game and you cannot get them back unless they are purchased with real money!
Hope this made sense! Please post back if you need further assistance or clarification!
See you around in the Community! Have a great rest of the day/evening!