Downloading and installing Facebook Messenger on iOS 4.2.1 is technically possible but highly impractical because official support has ended
If you previously downloaded Messenger on your Apple ID when you had a newer iOS device: facebook messenger ipa for ios 4.2.1 download
Then the message came that changed everything: a picture, grainy and sunlit, of their father at a barbecue, wearing the same ridiculous Hawaiian shirt he’d always hated. It was dated years ago, but seeing it again felt like an accidental gift. Maya wrote: “I thought I’d lost this forever.” Jonah typed back, hands clammy. The app hummed with the life of the past. Downloading and installing Facebook Messenger on iOS 4
Initially supported some late iOS 4 versions, but quickly moved to iOS 4.3 minimum iOS 12.4 and above The app hummed with the life of the past
(Internet Archive, Dropbox links, random forums). These are high-risk. Many files are mislabeled (e.g., "Messenger for iOS 4" turns out to be for iOS 6). Worse, malware authors love old IPAs as vectors for phishing or spyware, since modern antivirus tools rarely scan legacy formats.