Why after patching latest SQL Server 2017, connection to SQL instances must entered port number?

Question

I was patching SQL Server 2017 (svr1\insA and svr1\insB) together with following patches in the following order:

1. KB5016884 - Cumulative update 31 (CU31) for SQL Server 2017 
2. kb5029376 - CU Updates
3. KB5040940 - Security update for SQL Server 2017 CU31
4. KB5042215 - Description of the security update for SQL Server 2017 CU31 
5. KB5046061 - Description of the security update for SQL Server 2017 CU31 After the patches are completed, I am not able to connect to the named instances as normal. In order to connect to the instances, it requires to specify the port number. E.g. svr1\insA,1433 and svr1\insB,1434 The server svr1 is configured with Availability Group (AG), however, due to the patched, AG is not able to failover because unable to connect as svr1\insA. Please assist urgently.

Answer 1

Hi @Yee Beng Wong

Please check if the SQL Server Browser service is running.

If this service is not running, any component that tries to connect to a named instance without fully specifying all the parameters (such as the TCP/IP port or named pipe) don't work.

Please assist urgently.

If the situation is urgent, it is suggested to open a support case with Microsoft to troubleshoot the problem.

Best regards,

Cosmog

---

If the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".