Our stagging environment is on a single server with 3 virtual servers,

  • Database Server
  • K2 Workflow Server
  • WebFrontEnd Server

Now time to time I am getting this exception for a webpart in event log, not sure what could be the possible cause for this error.

The error was:

A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 0 - Only one usage of each socket address (protocol/network address/port) is normally permitted.)

Can anyone tell me what could be the possible issue to look at, I also noticed OWSTIMER.exe on web front end server is on top with most memory consumption however processor is alright, restarting Windows Service Timer job bring OWSTimer.exe back down but there isn't any workflow but custom timer job that runs each 15 minutes but then I checked with SP Dispose checker tool, its not leaking any memory.

2 Answers 2


Possibility 1: Firewall Rules

Double check your firewall settings in all the servers. A very basic connectivity test would be like - If your SQL Server is running on port 1433 , please do a telnet from K2 Server and the WFE Server to the SQL Server on port 1433.

Another possibility is if you are using a custom webpart with connectivity to sql based on certain connecting string , check your configuration files or related settings in the code. In all likelyhood , your SQL Server seems unreachable to either of your servers - k2 or wfe.

Possibility 2: Port Exhaustion

TCP/IP port exhaustion can occur on a client computer if the client computer is engaging in an unusually high number of TCIP/IP socket connections. This can occur if many client applications are initiating connections. - As quoted from Technet. From the context of sharepoint, the wfe servers are trying to initiate multiple connections on different ports.

You will need to follow this workaround on every web server as mentioned in this article. https://support.socketlabs.com/index.php?/Knowledgebase/Article/View/61


Real Problem was with Content DB as someone changed content DB for a web application to something that doesn't exists so when I type in URL it was trying to get that supplied content DB but then on failing it was going to default content DB in central admin.

Hope it helps other come across this error.

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