On Tuesday August 14, we published a Security Update for six different releases of SQL Server 2016 and 2017. For one of those releases, SQL Server 16 SP2 CU (KB4293807), we inadvertently published additional undocumented trace flags that are normally not on by default. We are working on replacing the update in the next few days. If you installed KB4293807 and are experiencing issues please uninstall the update until the replacement update (KB4458621) is available.
Thank you
SQL Server Release Services