Stuck WhatsApp iCloud backup at 99% after iPhone transfer on iOS 18.7.1

Hi everyone,

I’m facing a persistent WhatsApp iCloud backup issue that started after transferring data from one iPhone to another. I’ve already spoken to both Apple and WhatsApp support, but neither could resolve it. I’m hoping someone here has experienced this exact situation and found a working fix.

Context:

• Old device: iPhone 16 Pro
• New device: iPhone 17 Pro Max
• Both on iOS 18.7.1 (22H31)
• WhatsApp version: latest from App Store
• iCloud Drive toggled ON and confirmed working normally
• Ample iCloud storage available

The problem:

• WhatsApp backup is stuck indefinitely at “Preparing…” or reaches 99% and then fails.
• iCloud backups for the full device complete successfully, but WhatsApp no longer appears in my iCloud storage list.
• If the phone screen locks, the backup pauses. Even with Auto-Lock set to “Never”, it still stalls before completion.
• This started after I restored data to the new iPhone — backups had always worked fine before that.
• I’ve avoided reinstalling WhatsApp because there’s no confirmed backup and I risk losing all chat data.

Troubleshooting already done:

1. Logged out of iCloud and logged back in.

1. Updated to latest iOS (18.7.1).

1. Toggled iCloud Drive and WhatsApp backup permissions off/on.

1. Offloaded the WhatsApp app and reinstalled without deleting data.

1. Verified iCloud storage space (plenty available).

1. Tried on both Wi-Fi and hotspot.

1. Disabled Auto-Lock and kept WhatsApp open during backup.

1. Attempted backup multiple times — always stops at 99%.

Questions:

• Has anyone managed to fix a stuck WhatsApp iCloud backup (particularly after a phone transfer)?
• Is there a known cache or corruption issue that can be cleared without deleting app data?
• Does a full iPhone-to-iPhone transfer copy the local WhatsApp database even if the backup fails?
• Any verified method to reset WhatsApp’s iCloud backup state safely?

Any detailed guidance or success stories from people who’ve fixed this would be greatly appreciated.

Thank you in advance, I’ve spent days on this and just need a reliable way to get my data backed up safely before moving to the new phone.

[Re-Titled by Moderator]

Original Title: WhatsApp iCloud backup stuck at 99% on iOS 18.7.1 – tried all resets, offload, re-login, still failing