WhatsApp for Xiaomi Redmi Note 5 Pro

This is almost always MIUI's aggressive battery management killing WhatsApp after the update. Go to Settings > Apps > Manage apps > WhatsApp > Battery saver and set it to 'No restrictions', then on the same WhatsApp screen turn on Autostart. If it still misbehaves, open Settings > Apps > Manage apps > WhatsApp > Clear data and tap 'Clear cache' (not 'Clear all data'), then reboot. See how others solved this on Reddit

After a MIUI update the system often revokes WhatsApp's background data and autostart permissions. Re-enable them at Settings > Apps > Manage apps > WhatsApp > Autostart (toggle on), then open Settings > Apps > Manage apps > WhatsApp > Restrict data usage and make sure both Wi-Fi and Mobile data are checked. Also lock WhatsApp in the Recents screen by swiping down on its card and tapping the lock icon so MIUI stops clearing it from memory. See how others solved this on Reddit

Delayed notifications on Redmi phones come from MIUI's battery saver freezing WhatsApp in the background. Set Settings > Apps > Manage apps > WhatsApp > Battery saver to 'No restrictions' and turn on Autostart, then go to Settings > Apps > Manage apps > WhatsApp > Notifications and make sure 'Show notifications' and 'Floating notifications' are allowed. Finally, lock WhatsApp in the Recents screen so MIUI keeps it alive. See how others solved this on Reddit

First make sure WhatsApp is fully updated from the Play Store, since older builds crash on MIUI. If it still errors, go to Settings > Apps > Manage apps > WhatsApp > Clear data, tap 'Clear cache', and reboot. If the crash persists, back up your chats to Google Drive (in WhatsApp: Settings > Chats > Chat backup) and reinstall the app fresh. See how others solved this on Reddit

This usually happens because the proximity sensor thinks the phone is at your ear and switches playback to the quiet earpiece instead of the loudspeaker. Play the voice note with the screen clear of your hand and the phone away from your face, and clean the area around the top earpiece and proximity sensor. While a voice note is playing, raise the volume with the volume rocker (this adjusts media volume) to make it louder. See how others solved this on Reddit

Sudden shutdowns during calls are typically a worn or failing battery that can't hold voltage under the combined load of the radio and screen, which is common on older Redmi Note 5 Pro units. Check the battery health and consider a battery replacement, and meanwhile keep the phone above 30% charge during calls. To rule out software, boot into Safe Mode (hold Power, then long-press the 'Power off' option until prompted) and use the phone normally for a while - note that third-party apps including WhatsApp are disabled in Safe Mode, so if it never shuts down there, a buggy app or MIUI setting is the likely culprit rather than the hardware. See how others solved this on Reddit