Hey there fabriziosomano,
Thanks for reaching out to the Apple Support Communities. Just to confirm, were these the steps you tried when troubleshooting issues with backing up your WhatsApp conversations: Can’t create or restore an iCloud backup - WhatsApp Help Center
Can't create a backup
If you're unable to create an iCloud backup:
- Verify you're signed in with the Apple ID that you use to access iCloud.
- Verify iCloud Drive is turned on. Go to iPhone Settings > tap your name > iCloud > check that your iCloud Drive is on.
- Turn iCloud Drive off and back on. Go to iPhone Settings > tap your name > iCloud > turn iCloud Drive off and on.
- If you've turned on iCloud Drive for any device using your Apple ID, update to iOS 12 or newer to create a backup.
- Verify you have enough available space on your iCloud account to create a backup. You need to have at least 2.05 times the space available in your iCloud account than the actual size of your backup.
- If you're attempting a backup on a cellular data network, enable cellular data usage for iCloud.
- Perform a manual backup by going to WhatsApp Settings > Chats > Chat Backup > Back Up Now.
- Attempt the manual backup on a different network. Preferably the network you connect to the most.
If so, then the next best option would be to reach out to WhatsApp support directly from this link here: Contact WhatsApp
We hope that's able to help.
Take care!