Trouble with syncing messages to iCloud. Sync greyed out.

I'm experiencing the same issue (the “Sync this iPhone” toggle cannot be enabled because it is disabled). The suggestions above did not help.

I wonder if using Lockdown Mode prevents syncing messages with iCloud? What else might disable Messages syncing?

Hi Dbgolf2me,

To sync your Messages to iCloud, we recommend that you try the steps here: Set up iCloud for Messages on all your devices - Apple Support

To perform the recommended troubleshooting steps via the link above, complete the steps in the section titled "Set up iCloud for Messages on your iPhone, iPad, or iPod touch."

1. On your iPhone, iPad, or iPod touch, go to Settings > [your name] > iCloud.

2. Do one of the following:

* iOS 16, iPadOS 16, or later: Tap Show All, tap Messages, then turn on Sync this [device].

* iOS 15, iPadOS 15, or earlier: Turn on Messages.

Any messages currently stored in iCloud are now accessible on your device, and any new messages you receive on your device will be stored in iCloud.

3. To make sure you can see your messages on all your devices, also check the following:

* iMessage account: On your iPhone, iPad, or iPod touch, go to Settings > Messages > Send & Receive. Make sure that you’re signed in to iMessage with the same Apple ID. You can choose which email addresses and phone numbers you want to send and receive messages from on each device.

* Text message forwarding: If you want to receive SMS and MMS messages on all your devices, go to Settings > Messages > Text Message Forwarding on your iPhone. Turn on text message forwarding for each device. For more information, see the Apple Support article Forward SMS/MMS text messages from your iPhone to your Mac or iPad.

4. To see messages stored in iCloud, open the Messages app.

For more information on how to use Messages on your iPhone, iPad, or iPod touch, see any of the following:

* iPhone User Guide: Send and reply to messages on iPhone and Collaborate on projects with Messages on iPhone

* iPad User Guide: Send and reply to messages on iPad and Collaborate on projects with Messages on iPad

* iPod touch User Guide (iOS 15 or earlier): Send and receive text messages on iPod touch

We recommend the steps above because they will show you how to set up iCloud for Messages on all your devices.

If you’re still experiencing the same issue, then we recommend that you contact Apple Support directly so that they can work with you to find a solution. You can reach them by clicking here: Apple Support or calling the most local number in your region: Contact Apple for support and service. Thank you for participating in the Apple Support Communities. Cheers!