App closing automatically

See the troubleshooting steps here for an app that is not working correctly. If an app on your iPhone or iPad stops responding, closes unexpectedly, or won’t open - Apple Support This will also include contacting the app developer for assistance.

May be app needs update. Goto Appstore and update the app.

Usually they may not function well if we don't update them regularly.

If you followed all of the steps in the support document I provided, you would have contacted the app developer or their support. What did they have to say when you contacted them? They provide support for their apps, not Apple. If you did not contact them, then you have not done everything to correct it. Contact WhatsApp.

There have been quite a few complaints here recently regarding this issue.

Sounds like either WhatsApp released a buggy update or they have a problem on the back end.

You’ll have to deal with WhatsApp on this. it’s not an Apple problem.

WhatsApp is a 3rd party app, reach out to -> WhatsApp business

https://faq.whatsapp.com/smbi/?locale=en_US

You will need to keep trying.