If you have not yet spent free tasks at the festival and the game already asks you to pay diamonds for accepting the task, you can easily solve the problem - just clean the application cache.

Android:
1. Close the game completely
2. On your device go to Settings -> Applications.
3. Find My Cafe -> Memory -> Clean Cache.

After that everything will be back to normal and tasks will become free again.

iOS devices do not have a cache clearing feature, so you need to restart your device and check if the tasks are free again.

If these recommendations did not help and you had to buy tasks, please, contact our support agents and they will compensate the diamonds which you had to spend on the tasks.