We have a fantastic article for you to read here: android problems for when you are having problems with your game loading or crashing on you. You need to read this as it will help you.
The reason why I am also adding another post is because android also save data for you and sometimes uninstalling a game isn't enough. You also need to clear the system and game cache. Otherwise when you reinstall it, up pops the old data along with issues.
Personally before uninstalling I would make sure everything is clean and fresh as it can be.
Make sure you are synced with your previous method of saving data. Either Facebook or the Kingdom.
Remember doing this is usually worth trying as it will remove system errors, but it will remove your boosters as they are saved in the device memory. Maybe use them up first if you can?
You need to go to Settings > Apps > Google play store > Storage > Clear cache
Then go back to Settings > Apps > (The app you are having issues with) > Storage > Clear data, clear cache.
(IF YOU USE FACEBOOK AND ARE HAVING LOG IN PROBLEMS ONLY: Uninstall the Facebook app)
Uninstall the game app.
Reboot your device as in the article instructions.
Reinstall the app. Open it up and log in.
(If connection was your issue, do not reinstall the Facebook app at this point)
If it is working, brilliant, if not, follow the instructions in the linked article.
And if you find its working properly and you uninstalled the Facebook app you can now reinstall it as normal 
