1. Check your internet connection
This is the most common cause. WhatsApp needs a stable connection, whether over wifi or mobile data, to receive messages in real time. Open another app that needs the internet, like the browser or a maps app, and check whether it loads normally. If it's slow or won't load, the problem is with your connection, not WhatsApp.
Also try turning airplane mode on and off for a few seconds, or switching from wifi to mobile data (or vice versa), to force your phone to look for the best available signal again.
2. Check the battery saver
If your phone has a power-saving mode turned on, it might be restricting WhatsApp's background activity to use less battery. This causes the app to not receive push notifications until you open it manually, giving the impression that messages are "stuck waiting".
To avoid this, go to your phone's Settings โ Battery (or Apps โ WhatsApp โ Battery) and turn off battery optimization or power saving specifically for WhatsApp. It's also worth checking that the app is up to date: go to Google Play or the App Store, search for WhatsApp and, if there's a pending update, install it, since older versions may have connection bugs that have already been fixed.
3. Incorrectly set date and time
WhatsApp uses security certificates that require your phone's date and time to match the real time. If they're off, even by mistake, the app can fail to establish a secure connection with the server and stop receiving new messages.
Go to your system's general settings and turn on "Automatic date and time" (or "Use network-provided time"), instead of having it set manually.
4. Check whether the problem is WhatsApp's servers
If you've checked everything above and still aren't receiving messages, the fault might not be on your phone, but on WhatsApp's own servers. These outages are usually temporary and affect many users at once. You can check this on websites that monitor the status of online services: if they detect a widespread issue, all that's left is to wait for WhatsApp to fix it on their end.