You can install an old Facebook IPA on iOS 7.1.2, but it will not function fully. You might be able to log in and see old messages, but News Feed, Stories, and Messenger will break.
If you still want to try, here are the typical sources where legacy IPAs are archived. Downloading IPAs from third-party sites is risky. Files may contain malware, trackers, or stolen credentials. Facebook Ipa Ios 7.1 2 Download
Let’s face it: iOS 7.1.2 is a museum piece. Use these devices for old games (Flappy Bird, Infinity Blade), music, or as a dedicated e-reader. For Facebook, any Android phone from 2018+ or an iPhone 6s on iOS 15 is a more practical choice. You can install an old Facebook IPA on iOS 7
If you found an IPA online, you can sideload it using Sideloadly (works on modern Windows/Mac) with a free Apple ID. However, iOS 7.1.2 does not support the modern AppSync or developer disk images easily — you may need a jailbreak. Downloading IPAs from third-party sites is risky