The mobile site uses standard web protocols that are more likely to be compatible with older browsers than the proprietary API calls used by the 2011-era app.
The primary hurdle is that Facebook’s server-side protocols have changed drastically since iOS 4 was current. facebook messenger ipa for ios 4.2.1 download
Use a tool like iFunBox on a PC to drag and drop the .ipa file into the "User Applications" directory of your device. The mobile site uses standard web protocols that
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 newer device or iTunes on a
For those with a jailbroken device, you can manually install .ipa files found in web archives like Archive.org .