Use a tool like iFunBox on a PC to drag and drop the .ipa file into the "User Applications" directory of your device.
Because the native app often fails to connect to modern servers, the most reliable way to access Facebook Messenger on iOS 4.2.1 is through the . Navigate to: m.facebook.com facebook messenger ipa for ios 4.2.1 download
Use a newer device or iTunes on a computer to "buy" (download) Messenger on your Apple ID. Step 2: Open the App Store on your iOS 4.2.1 device. Step 3: Go to "Purchased" and try to download Messenger. Use a tool like iFunBox on a PC to drag and drop the
The primary hurdle is that Facebook’s server-side protocols have changed drastically since iOS 4 was current. Step 2: Open the App Store on your iOS 4
You can still send and receive basic text messages via the mobile web interface without needing a separate Messenger app. Troubleshooting Potential Issues Operating systems that support the Messenger app - Facebook
Apple introduced a feature in late 2013 that allows users to download the last compatible version of an app if they have previously "purchased" it on their Apple ID.