"Anybody is facing issues with WhatsApp after updating to iOS 9 and especially 9.3.2? I have iPhone 6s and WhatsApp always freezes. It can't type and keeps connecting even though there is Internet. " - User from Apple Support Communities
Obviously, WhatsApp has been causing a lot of troubles to iPhone users. Earlier, users faced in WhatsApp crashing on iOS 8, and now many users are facing WhatsApp crashing issue in iOS 11/10 on iPhone as well. The problem is now spread across a variety of possible causes. I have found some fixes that have proved to be working for quite a few fellows. I am not sure if they will work for you, but it's better to give them as try. These methods are supplied to iPhone X/8/8 Plus, iPhone 7/7 Plus, iPhone SE/6s/6s Plus/6/6 Plus, iPhone 5s/5c/5 and other iOS devices.
How to Fix WhatsApp Crashes on iOS 11/10/9
We will try to keep things simple in the beginning and keep the painful processes for later. So first of all, uninstall the WhatsApp app from your iPhone and then install it again from the App Store. Just give it a try. After that you can check whether WhatsApp is back to normal, if it isn't, keeping reading below.
One workable way to fix WhatApp crashing in iOS 9 on iPhone could be iCloud drive. Disabling iCloud Drive is easy.
Go to Settings -> iCloud, tap on iCloud Drive, turn off the switch.
This method seems to have randomly worked in fixing WhatsApp crashes for part of users. So give it a try.
One of the culprits causing WhatsApp crashed could be the iCloud backups. There are a number of factors which might result in a failed backup, and it is next to impossible to determine each and everyone. The easiest way is to disable this option and use WhatsApp peacefully. You'll just need to open WhatsApp → Settings → Chats → Chat Backup → Auto Backup → Turn it Off.
If you have recently updated the Facebook app to the latest version, and also you have enabled contact sync between Facebook and iPhone, then this could be the issue. That's because WhatsApp resizes the images in the Contacts app. As the images are derived from Facebook, you should consider disabling contacts sync with Facebook. To do so, go to the Settings app on iPhone → Facebook → toggle off "Contacts".
Delete contact picture
If you are still reading, then it means that simply disabling contacts sync with Facebook hasn't helped you. Let's take it a step further, delete images from all the contacts and check if WhatsApp is revived or not. Open Contacts → tap on a contact with image → Edit → tap Edit below the image → Delete Photo. It's a bit of a tedious process, but that should work.
Before proceeding with the reset, make sure you make a fresh backup with iTunes. Then go to Settings → General → Reset → Erase all Content and Settings. After your iPhone has been reset, restore it using iTunes. But make sure you don't restore the apps. It's better to make a fresh download of WhatsApp from App Store. Or you can repair your iPhone operating system via the third-party software, like iPhone Care Pro. It's a world-class and professional systemcare tool to solve WhatsApp freezing on iOS 9 problem, optimize your iPhone and repair iOS crashes, severe damage and other stuck issues.