For Android users:
Please try the following steps to solve the issue:
1. Go to the device Settings
2. Tap Apps
3. Select Manage Apps
4. Choose the game
5. Tap "Force Stop"
6. Tap "Clear Cache"
If the issue persists, please try reinstalling the game.
Don't forget to log in to your social network account to recover your game progress.
For Apple users:
To solve the issue, please delete the game from your device and iTunes:
1. Go to the device Settings
2. Tap General
3. Select iPhone Storage
4. Choose the game
5. Tap "Delete App"
Then download it from the App Store again. Once the game is installed, reboot your device and launch the game.
Don't forget to log in to your social network account to recover your game progress.