Well, if the app has accumulated a lot of caches, then it can cause issues with it and lead to
WhatsApp Backup Stuck on Android being stuck on Android. To fix this, you can go to your device's Settings > Apps/Application Manager and select WhatsApp. Go to its Storage and tap on the “Clear Cache” button to reset its cache data.Why WhatsApp backup is stuck? When lots of apps are running in the background the also there is a chance that WhatsApp backup gets stuck. Therefore, you just need to close all the apps running in the background. Simply click on the app switcher icon and all apps running in the background will occur.