App keeps crashing after an update: what to try, in order

Start with the cheap fixes

1. Force stop and reopen: Settings › Apps › the app › Force stop.
2. Clear cache: same screen › Storage › Clear cache. No data is lost.
3. Reboot the phone. Updates to shared components take effect only after a restart on some devices.
4. Update Android System WebView and Chrome in Google Play. A large share of "every app crashes" incidents, including the widely reported one in 2021, came from a broken WebView update; many apps render parts of their interface with it.
5. Update Google Play services. Apps using Google sign-in, maps or push notifications crash when the services version is too old for the app's library.

If the app still crashes

1. Clear storage (Settings › Apps › the app › Storage › Clear storage). This resets the app to a fresh install; you will need to sign in again. Export anything the app keeps locally first.
2. Check free space and memory. Under 500 MB free or an aggressive battery optimiser killing the app in the background both look like crashes.
3. Turn off battery optimisation for the app on Xiaomi, Huawei, OPPO and Samsung devices, which are known for killing background processes.

When the update is the bug

If the app worked before the update and the crash started immediately after, the previous version is the reliable fix. The app's version page here lists earlier builds with their dates; pick the one you had, uninstall the current version and install it as described in how to downgrade an app. Turn off auto-update for that app in Google Play so it is not replaced again, and check back in a week or two for a fixed release.

Finding the reason

Without a computer, LogFox or Logcat Reader (F-Droid) can capture the crash log. With a computer, adb logcat *:E while reproducing the crash shows the exception, which is what to search for or send to the developer. Crashes mentioning WebView, GmsCore or Resources$NotFoundException point to the WebView, Play services and missing-split causes above respectively.