Make sure your game has the latest version installed. Please see the steps from the links provided below:

For iOS: http://zynga.my/1Uel9VB

For Android: http://zynga.my/UpdateAndroid

For Kindle: http://zynga.my/UpdateAmazonKindle

For Windows Phone: http://zynga.my/FV2CEWindowsPhone

For Windows 10 PC/Laptop: http://zynga.my/1SNChxW

In case you're still experiencing the issues after updating, you may try these troubleshooting steps if you haven't done it yet:

For iOS: http://zynga.my/FV2CEiOS

For Android: http://zynga.my/FV2CEAndroid

For Kindle: http://zynga.my/FV2CEKindleFire

For Windows phones/tablets: http://zynga.my/FV2CEWindowsPhone

For Windows 10 PC/Laptop: http://zynga.my/1SNChxW

Furthermore, older models of the iPad and iPad Mini do not support all features of the game which may lead to crashing.