This most likely means that the cache file is corrupted. Please try refreshing the SwiftKey Store. If this does not work, you should refresh your cache.
Note: this will clear all data and saved language from the application. If you would like to keep your language data, please make sure you are signed into SwiftKey Cloud and have “Backup & Sync” enabled.
Open your device System Settings
Tap App Manager/Appps
Find and tap ‘SwiftKey’
Tap ‘Clear data' and 'Clear cache'
Open SwiftKey Keyboard and make sure that all of your settings are how you like them
If the previous steps did not work, try reinstalling an updated version of SwiftKey Keyboard.
If the problem persists, please report this to the Support Team by clicking the green 'Submit a Request' button on this page.