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With a recent update this could be a bug or some other mundane issue. We'll need more information to offer more than guesses and maybes.
What device do you have?
What was the update? The app, the OS, security patch?
You might try to restart the device. While the device may have restarted during the update it doesn't hurt to perform another when it is all over. Restarts close programs, clears caches and reopens vital processes.
Have you cleared the cache for WhatsApp manually? While restarts should clear caches and keep things running there are times, usually after an update, when things can be missed. To manually clear the cache, Settings>Applications>WhatsApp>Storage>Clear cache.
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