Failed to transfer whatsapp data from android to ios

I need to admit that I would usually think about this as a WhatsApp-issue, and not as a problem with your iPhone.

I'll look it up though.

Edit:

Meta says this:

Device setup

Check the list below before moving chats:

* Both devices are plugged in.

* Both devices are connected to the same Wi-Fi.

* Your iPhone is a new one or factory reset.

* You’re using the same phone number on your old phone and new phone.

* Android 5 or above is installed on your Android device.

* iOS 15.5 or above is installed on your iPhone.

* Move to iOS app is installed on your Android device.

WhatsApp is already active on my iPhone

You can only move your chats before you’ve activated WhatsApp on your iPhone. If you want to retrieve your old chat history:

1. Factory reset your iPhone.

2. Reinstall WhatsApp on your Android device.

3. Start a new transfer with the Move to iOS app on your Android device.

Note: You can’t merge new chats from your iPhone with old chats from your Android device.

Error messages:

If you receive the error message “An unknown error occurred. Please try again later,” your chat history may be corrupted. We recommend restarting both phones and trying again.

WhatsApp is not an Apple Product. You'll need to get help from WhatsApp support.

https://www.whatsapp.com/contact