WhatsApp for Samsung Galaxy F15

Samsung's aggressive battery management is the usual cause. Go to Settings > Apps > WhatsApp > Battery and set it to Unrestricted. Then open Settings > Battery > Background usage limits and make sure WhatsApp is not in the 'Sleeping apps' or 'Deep sleeping apps' lists (remove it if it is). In that same Background usage limits screen, turn off 'Put unused apps to sleep' so One UI stops freezing WhatsApp in the background. Finally, confirm notifications are enabled under Settings > Apps > WhatsApp > Notifications. See how others solved this on Reddit

The cloned (Dual Messenger) WhatsApp stores its media separately from the normal WhatsApp folder. Open My Files, tap the three-dot menu and enable 'Show hidden files', then look under Internal storage > Android/media for a folder tied to the second instance (the dual-app clone uses its own package directory, separate from the standard com.whatsapp folder). The most reliable way to keep that clone's chats is to back them up from inside the cloned app itself via WhatsApp Settings > Chats > Chat backup, which saves to the Google account linked to that instance. See how others solved this on Reddit

The Galaxy F15 5G has a 3.5mm headphone jack, so standard analog earphones should plug in directly and work for calls. First reseat the plug fully, as a partial connection often breaks the microphone while still passing audio, and clean any lint out of the jack. During a WhatsApp call, tap the on-screen audio/speaker icon to confirm output is routed to the headset rather than the earpiece or speaker. If the mic still fails, test the same earphones on another device to rule out a faulty cable, and try a different pair to confirm whether the issue is the earphones or the phone's jack. See how others solved this on Reddit

This appears when WhatsApp detects a modified or sideloaded build (such as GB/Yo WhatsApp), so uninstall whatever version you have and reinstall WhatsApp only from the Google Play Store. If you used a mod to keep old chats, export a chat backup from inside it first, then sign in to the official app and restore from your Google Drive backup linked to the same Google account. Also set Settings > General management > Date and time to automatic, since a wrong clock can trigger this verification error. See how others solved this on Reddit

If the old phone is dead but your chats were backed up to Google Drive, install WhatsApp from the Play Store on the F15, verify the same phone number, and choose Restore when prompted (the backup must be on the same Google account). If the old device still works, use Samsung Smart Switch via Settings > Accounts and backup > Bring data from old device, which can transfer app data over Wi-Fi or cable. Without any prior backup, older messages can't be recovered, so once you're set up, enable Settings > Chats > Chat backup on the F15 to protect future chats. See how others solved this on Reddit

WhatsApp has a built-in lock: open WhatsApp > Settings > Privacy > App lock and turn on Fingerprint unlock so chats require your fingerprint to open. For a stronger system-level option that also hides the app and its notifications, set up Samsung's Secure Folder via Settings > Security and privacy > More security settings > Secure Folder, then add a separate WhatsApp instance inside it. Samsung's native tools are safer than third-party app lockers, which often demand excessive accessibility and overlay permissions. See how others solved this on Reddit