This is not limited to SQL 2019, my issue is that suddenly on 1/8 all the linked servers on various SQL servers, that use Windows authentication, stopped working due to delegation failure ("Login failed for NT AUTHORITY/ANONYMOUS LOGON"). Kerberos authentication works fine on all servers, but not delegation.
This applies to a variety of SQL server versions, 2005 through 2016, across the whole domain. It also affected SSRS reports and Tableau reports using Windows Auth data sources.
My company has two domains with trust relationships. In one domain delegation is not working anywhere. In the other domain delegation is mostly working (only three broken links, on one server), even across the domain boundary.
I can't find any Windows patches that were installed anywhere near when this started. Our infrastructure can't push patches to all servers simultaneously in any event, so I can see how a server patch caused this. One theory is that it could be something installed on a domain controller.
One website I looked at said there was an update in July 2019 that disabled unconstrained delegation at AD forest boundaries by default. All of our servers are set up with unconstrained delegation. The problem with this explanation is that most of the broken links are with the same domain (do not cross a forest boundary), and in the other domain there are a number of links still working find, to servers in the problem domain.
Any suggestions would be appreciated.