Hello Mike-A,
Thanks for using Apple Support Communities.
I see that you are having an issue using Outlook with iCloud for Windows. After you made sure that the Outlook Add-in is on and restarted iCloud, iCloud stopped the sync and you received an error message. I can imagine that it's concerning to have an issue with something that previously worked perfectly. I'm happy to help assist you in finding the best resolution.
Use the article Get help using Outlook with iCloud for Windows, specifically, these sections:
If you have multiple iCloud accounts, you might be logged in to iCloud for Windows with a different account than you are on your other devices. To check, open iCloud for Windows and compare it with your other devices.
If you recently made changes in Outlook that aren't updating on your other devices, or changes on your other devices that aren't updating in Outlook, click Refresh in Outlook.
You can change your Outlook settings so that emails are automatically sent from your iCloud account. To make iCloud the default account, follow these steps:
If you're using Outlook 2010:
- Go to File > Account Settings.
- Click Email.
- Choose your iCloud account from the list, then click Set as Default. If you can't click Set as Default, then your iCloud account is already the default account.
The iCloud Outlook Add-in transfers your content between iCloud and Outlook. Follow these steps to turn on the Add-in:
In Outlook 2010 and later:
- Select the File menu.
- Click Options in the left panel.
- Click Add-ins in the left panel of the Outlook Options window.
- Look at the list of add-ins in the Active Application Add-ins section.
- Select the iCloud Outlook Add-in.
When iCloud is set as your default account in Data Files, your data won't sync between your devices.
Outlook 2010 and later:
- Select File > Info > Account Settings > Data Files.
- If iCloud is listed as the default account in the Comments column, select a different account.
- Click Set as Default.
Turn your computer off and back on.
Some iCloud features in Outlook work differently than they do on your Apple device. Here are a few tips to help you use Outlook with iCloud for Windows.
- VIP Senders folders aren't available in Outlook.
- Any mail rules that you create in Outlook aren't available in the mail applications for your other devices or on iCloud.com.
- Signatures are saved locally to your device. You won't see signatures you create in Outlook on your other devices.
Notes isn't a separate application. Your notes are stored in a mail folder.
- You'll find Notes that you create on your other devices in this folder.
- Notes that you post to this folder from Outlook won't appear on your other devices, but you'll see them on any other computer using Outlook and iCloud for Windows when you're signed in with the same Apple ID.
- You can delete notes from this folder and they'll be deleted from your other devices.
- Outlook will only import the first contact in a vCard set.
- If you need to add a vCard set to Outlook, import the set directly into iCloud.com or OS X Contacts. We will bundle the entire set for you and add them as individuals to the your Contacts.
When you add Calendar attachments to a Calendar entry in Outlook, you won't see them in Calendar for iOS, Calendar for OS X Mountain Lion, or iCal. (or the other way around)
Like Calendars and Contacts, you need to enter your Reminders in the iCloud section of Tasks in Outlook. If you don't enter your Tasks into the iCloud section, they won't transfer to iCloud.
Best Regards.