Connection Error 233 : No process at the other end of the pipe

Just had an interesting error the other day.

Got this error when trying to connect one of our servers that has just been patched:

A connection was successfully established with the server, but then an error occurred during the login process. (provider: Shared Memory Provider, error: 0 – No process is on the other end of the pipe.) (Microsoft SQL Server, Error: 233)

Typically, to troubleshoot this, you go to SQL Server Configuration Manager (SSCM) and:
1. ensure Shared Memory protocol is enabled
2. ensure Named Pipes protocol is enabled
3. ensure TCP/IP is enabled, and s ahead of the Named Pipes in the settings

Check out Pinal Dave’s excellent post on this.

All of these are set in our server.

Next up, I checked the log files. Logs are typically located in a folder similar to this (note you will need to change the folder MSSQL.1 with the appropriate instance name’s folder name):
C:Program FilesMicrosoft SQL ServerMSSQL.1MSSQLLOG

When I checked the logs however, I got yet another interesting error:

Could not connect because the maximum number of ‘1’ user connections has already been reached. The system administrator can use sp_configure to increase the maximum value. The connection has been closed. [CLIENT: ]

It’s an interesting error because:
1. We just restarted the server and nobody is able to access it yet
2. DAC is disabled

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