I wrote the following code in my feature receiver to add a connectionString in the web.config:

SPWebApplication webApp = SPWebApplication.Lookup(new Uri("http://devtools2012/sites/Test"));

SPWebConfigModification mod = new SPWebConfigModification("add[@name=\"MyConnection\"]", 

    mod.Owner = "ExcelServiceOwner";

    mod.Type = SPWebConfigModification.SPWebConfigModificationType.EnsureChildNode;

    mod.Value = String.Format("", "MyConnection", "Server=DEVWCMSDB2012;Database=BJS;Integrated Security=true", "System.Data.SqlClient");




However, it is failing with the following error:

Failed to apply web.config modifications to Web application '9a38b727-bab9-44ad-93ba-a6c3b919d481'. Failed to apply web.config modifications to file 'C:\inetpub\wwwroot\wss\VirtualDirectories\80\web.config'. The Value property for EnsureChildNode cannot be set to an empty value.

I appreciate any input you can extend me. Regards.


1 Answer 1


Unless it's a formatting issue with the question then the mod.Value = String.Format("", ...) is giving an empty string.

You want something like:

mod.Value = String.Format("<add name="{0}" connectionString="{1}" ProviderName="{2}" />", ...)
  • 1
    Per, thank you for the prompt response. Much appreciated...it works!!!! Regards. Apr 12, 2016 at 13:47

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