To keep Messenger running smoothly on older hardware:
Google to Finally Drop Remaining Support for Android 4.4 KitKat Facebook Messenger Apk For Android 4.4.4
Go to Settings > Security and toggle on Unknown Sources to allow installation of apps from outside the Play Store. To keep Messenger running smoothly on older hardware:
To get Messenger working on KitKat, you must manually install (sideload) an older version. Based on archive data, the following versions are known to support Android 4.4+: the most stable
After extensive testing and user community feedback, the most stable, secure, and fully functional version of Facebook Messenger for Android 4.4.4 is: