Hate to resurrect a dead thread, but thanks so much! This was exactly the issue in my case, although the situation was different.

I am slowly migrating a domain from Windows Server 2012 Essentials to Windows Server 2016. Up until now, AD Sync was being handled by the Office 365 Integration plugin for the Windows Server Essentials dashboard. But when I uninstalled that, it deleted all the records, which I couldn't find because I didn't know how to get a list of deleted users. So I spent the better part of today researching this to no avail, while in the meantime I'm receiving sync error notification emails every 30 minutes.

Once I manually deleted the users from the recycle bin, I forced an initial ADSync cycle and we're back in business.

So thankful to finally have this issue resolved!

Hate to resurrect a dead thread, but thanks so much! This was exactly the issue in my case, although the situation was different.

I am slowly migrating a domain from Windows Server 2012 Essentials to Windows Server 2016. Up until now, AD Sync was being handled by the Office 365 Integration plugin for the Windows Server Essentials dashboard. But when I uninstalled that, it deleted all the records, which I couldn't find because I didn't know how to get a list of deleted users. So I spent the better part of today researching this to no avail, while in the meantime I'm receiving sync error notification emails every 30 minutes.

Once I manually deleted the users from the recycle bin, I forced an initial ADSync cycle and we're back in business.

So thankful to finally have this issue resolved!