I'm having the same issue for my home and office computer, which are synced via icloud, both using Office 365 on Windows 10 Pro. I attempted to have a Microsoft Tech resolve the issue for me, they couldn't fix the issue, and blamed the issue on being an apple add-in issue. I called Apple, who said "Absolutely Not! It's a Microsoft Office issue, they must fix it." So it seems that each are blaming one another and leaves the issue unresolved, and nowhere to turn. Two final point, I am able to make all changes to my contacts on my iPhoneX as Microsoft says there are no add-ins on the phone like you do on the computer. I am able to create a new contact, but the minute I save it, I am unable to make any changes to it and receive the error message.
If anyone finds out how to resolve the problem, I would love to hear how.
Below are the steps that were taken by the Microsoft Tech. However, none of these fixed the issue.
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-signed-out account from iCloud app
-deleted following keys that contain Apple.DAV.Addin:
HKEY_CLASSES_ROOT\WOW6432Node\CLSID\{FF982CA0-9F7A-42d5-82B8-155B74904925}
HKEY_CLASSES_ROOT\Apple.DAV.Addin
HKEY_CLASSES_ROOT\CLSID\{D9BB00EA-0FB5-4032-AD67-65C6E0CDEDC0}
HKEY_CLASSES_ROOT\WOW6432Node\CLSID\{D9BB00EA-0FB5-4032-AD67-65C6E0CDEDC0}
HKEY_CURRENT_USER\Software\Apple Computer, Inc.
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Office\Outlook\Addins\Apple.DAV.Addin
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Apple.DAV.Addin
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Outlook\Addins\Apple.DAV.Addin
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\ClickToRun\REGISTRY\MACHINE\Software\Wow6432Node\Microsoft\Office\Outlook\Addins\Apple.DAV.Addin
-deleted Apple.DAV.Addin value in these keys:
HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Addins
HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\Addins
HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\CustomUIValidationCache
HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AddInLoadTimes
HKEY_USERS\S-1-5-21-*\Software\Microsoft\Office\16.0\Common\CustomUIValidationCache
HKEY_USERS\S-1-5-21-*\Software\Microsoft\Office\16.0\Outlook\AddInLoadTimes
-deleted these keys:
HKEY_USERS\S-1-5-21-*\Software\Apple Computer, Inc.
HKEY_USERS\S-1-5-21-*\Software\Microsoft\Office\16.0\Outlook\Addins\Apple.DAV.Addin
-search Apple.DAV.Addin in the registry and deleted any keys or values
-uninstalled all Apple apps
-rebooted PC
-installed iCloud from Apple website
-synced iCloud to Outlook (done)
-run following commands in Windows PowerShell admin:
Get-AppxProvisionedPackage -Online | where-object {$_.packagename –like "*Outlook*"} | Remove-AppxProvisionedPackage -Online
Get-AppxPackage "*Outlook*" | Remove-AppxPackage
-run Get-AppxPackage "*Outlook*" | Remove-AppxPackage command in just Windows PowerShell
-enabled compatibility for the iCloud app