So you’ve set up mirroring for your Lync front ends, and you know you need that witness for automatic failover. You’ve decided to use SQL Express so you don’t need another full license for this, but when you try to specify it as the witness, you get the following error:
Error: An error occurred: “Microsoft.SqlServer.Management.Common.ConnectionFailureException” “Failed to connect to server sqlwitness.domain.com\lyncwitness.”
It’s not a firewall or port issue, it’s not a permissions issue, it’s just not working. Here’s the trick: by default the SQL Browser Service is disabled with a SQL Express install. Set this service to automatic and start it up. You may need to remove the witness from your topology, publish, add it back in and republish, but you should be fine after this.