For iOS: Sign out of your Apple ID, restart your phone, and sign back in. Date and Time Settings
Verify if your OS version (Android or iOS) meets the current Messenger requirements. why can't i download messenger
If you are trying to stay connected with friends but the download button just won't cooperate, you aren't alone. Errors with the Facebook Messenger app are common, but the solutions are usually straightforward. For iOS: Sign out of your Apple ID,
A weak or unstable connection is the most frequent culprit. App stores often block downloads over a certain size if you are using cellular data to prevent overage charges. Toggle your Airplane Mode on and off. Switch from mobile data to a stable Wi-Fi network. Errors with the Facebook Messenger app are common,
Clear the cache of your existing apps to free up "hidden" space. Compatibility and Software Updates