If the app freezes on launch or crashes right away, start with the basics: force-close it, clear the cache (Settings → Apps → Facebook → Clear Cache), then reopen. If that doesn't help, check whether an update is available — outdated versions often break after server-side changes. Reinstalling the app fixes the issue in most cases.
A failed login is usually one of three things: wrong password, browser cache interference, or a session conflict across devices. Try logging in from an incognito window first. If it works there, clear cookies and cache in your main browser. For the mobile app, log out from all sessions via Settings → Security → Where You're Logged In, then sign back in.
When messages get stuck or don't show up on the other end, the problem is often a flaky connection rather than the platform itself. Check your signal strength or switch between Wi-Fi and mobile data. If the connection is fine, log out and back in — this resets the messaging session. Also check that Messenger has permission to run in the background.
If the feed stops scrolling or the UI becomes unresponsive, it's often a memory issue on the device side. Close other apps running in the background and try again. On desktop, check how many tabs are open — Facebook is memory-heavy. Reloading the page (not just refreshing the tab) usually clears the freeze.
Broken search is almost always a cache or account session issue. Clear the app cache, sign out, sign back in, and try again. On desktop, a hard refresh (Ctrl+Shift+R) helps flush stale data that can interfere with search indexing.