I was doing some testing and found out that our development servers went haywire and started randomly giving me that error. If I did a refresh, it looks like sometimes it would go through and other times it wouldn’t. Here are a couple things to try out if you haven’t already…
1. Verify that the SQL Services are running on the database server.
2. Make sure the service account of the central administration app pool has dbo rights to the database.
3. Did you or someone change the service account password? Change it back to the old password if you can.
4. Check your firewall settings. you should be able to ping the database server from your application or web servers, and vise versa. Make sure that the Inbound Rules have a Rule that states TCP port 1433 and UDP port 1434 open on your database servers.
5. Make sure Named Pipes is ON. Go to your SQL Server Configuration Manager on your database server. Under your SQL Server Network Configuration, select your SharePoint instance (most of the time its the default instance). Make sure Named Pipes is enabled. Many people think this isn’t necessary, but I’ve found it to be a must.
6. Another thing people miss is the TCP/IP ports. If you right click the TCP/IP protocol in the same setting as above, goto properties. Go to IP Addresses and make sure that the instance TCP Port on all IP1-IP5 is on 1433.
If you have any other suggestions you would like to input, I’d be happy to add them from comments…