I had this issue also it is really annoying, but let me tell you how to fix it. For me it happened when i had to many chats in my chatlist. And you need to delete some chats before wazapp will work properly. But if you start up wazapp it will close when it connects. Disable your network connection start wazapp and now you will have some more time to delete chats before it closes. This worked for me, try it.