WhatsApp for Samsung Galaxy Express I8730

The Express I8730 shipped with Android 4.1/4.2 Jelly Bean, and current WhatsApp builds no longer support such old Android versions, so the app can become unstable or stop updating from the Play Store. First clear its cache via Settings > Application manager > WhatsApp > Clear cache, then reopen the app. If it still misbehaves, the practical fix is to install the last WhatsApp version that supported Jelly Bean rather than forcing the newest build, since this hardware has aged out of WhatsApp's minimum OS requirements. Keep an eye on WhatsApp's official end-of-support notices, because at some point the app stops working on this OS entirely. See how others solved this on Reddit

After a WhatsApp update or a reboot, the notification settings can reset, or the system stops it running in the background. Open WhatsApp > Menu > Settings > Notifications and confirm message tones, pop-ups and vibration are enabled, then check Settings > Application manager > WhatsApp and make sure 'Show notifications' is ticked. If you use Power saving mode, turn it off under Settings > Power saving mode so WhatsApp can keep its background connection and deliver pushes while the screen is off. See how others solved this on Reddit

On Jelly Bean devices, completely missing notifications are usually caused by a restricted background data connection or a dropped push connection. Make sure background data is allowed by checking that 'Restrict background data' is off under Settings > Data usage, and keep the connection alive while idle via Settings > Wi-Fi > (Menu) Advanced > Keep Wi-Fi on during sleep > Always. Restarting the phone after these changes forces WhatsApp to re-register with its notification servers, which usually restores alerts. See how others solved this on Reddit

Delayed bursts happen when the phone puts the network to sleep to save power and then dumps everything when you wake it. Turn off any power saving under Settings > Power saving mode, and stop Wi-Fi from sleeping via Settings > Wi-Fi > (Menu) Advanced > Keep Wi-Fi on during sleep > Always. Clearing the WhatsApp cache via Settings > Application manager > WhatsApp > Clear cache can also help the push connection stay alive instead of reconnecting in bursts. See how others solved this on Reddit

This phone has limited internal storage, so a nearly full memory often stops WhatsApp from saving incoming media. Free up space, then confirm auto-download is enabled under WhatsApp > Menu > Settings > Chat settings > Media auto-download for both mobile data and Wi-Fi. If media downloads but never shows in the Gallery, the WhatsApp Images folder likely contains a hidden '.nomedia' file that hides it from the Gallery scanner; use a file manager to delete that '.nomedia' file (do not create one), then reboot so the Gallery re-scans the folder. See how others solved this on Reddit

Duplicate or repeating alerts usually come from a stale notification cache or from WhatsApp being open on the phone and on WhatsApp Web at the same time. Clear the cache via Settings > Application manager > WhatsApp > Clear cache, then log out of any browser sessions from WhatsApp > Menu > WhatsApp Web > Log out from all computers. Finally, toggle notifications off and back on in both Settings > Application manager > WhatsApp and WhatsApp > Menu > Settings > Notifications to reset the behavior. See how others solved this on Reddit