For devices running (such as the iPad 2, iPad Mini 1, or iPhone 4S), the modern Facebook app is no longer directly compatible as it typically requires iOS 15.1 or later

Downloading a verified Facebook IPA for iOS 9.3.5 can be difficult because the official App Store now requires at least iOS 13.4. While unverified IPA files exist on sites like Archive.org , they often crash or fail to connect to modern Facebook servers.

Method 1: The "Purchased" Section (No Computer/No Jailbreak)

Note: If you haven't "purchased" it before, download Facebook on a newer device using the same Apple ID first, then it will appear in the "Purchased" tab of your old device. 2. Sideloading a Verified IPA File

How to download Facebook IPA for iOS 9.3.5