I tried to create a web application today but got a vague unknown error message from SharePoint.  I looked in the Event Viewer and found this error message:

Unknown SQL Exception 10054 occured. Additional error information from SQL Server is included below.

A transport-level error has occurred when sending the request to the server. (provider: TCP Provider, error: 0 - An existing connection was forcibly closed by the remote host.)

I thought something was wrong with the network connection, that’s why the connection was forcibly closed.  So, I checked the connection to the SQL Server, but couldn’t find any problems.  What’s the deal?  After an hour of banging my head, I found that this error only shows up when I provide a load-balanced URL for the application.  I pinged the URL and guess what?  It didn’t reply. 

After working with the network engineers to fix the load balancer, I was finally able to create the web application that points to the load-balanced URL.  Very misleading error message...