I am experiencing a "Target principal name is incorrect" error after upgrading SQL Server 2016 to 2017. The SQL Server 2016 instance has been uninstalled. The certificate which is registered in SQL Server Configuration Manager Protocols and is used to enable wire encryption is named with the FQDN of the server. It is the exact same certificate that was working successfully with SQL Server 2016.

I have noticed since the upgrade that I cannot logon to SQL Server 2017 using the FQDN of the server. I can only logon using [HOSTNAME]\[INSTANCE_NAME]. Why has this behaviour changed and how can it be restored? I am wondering whether restoring this behaviour will simultaneously resolve this connection error.

  • Check the SPN perhaps? Maybe this will help: dba.stackexchange.com/questions/180064/… – Jacob H May 9 at 12:52
  • What protocols have you enabled? – McNets May 9 at 12:55
  • @McNets I don’t have access to the machine right now but I believe TCP/IP only – Guru Josh May 9 at 14:25
  • Was the old instance running a named instance or default instance? Have you tried connecting via [FQDN][INSTANCE NAME] ? – HandyD May 10 at 5:20
  • Did you try with port number while connecting, does it work? – Learning_DBAdmin May 11 at 13:01

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