SQL Server Error "Could not open a connection to SQL Server"

Question

Hello. I know this is a known issue. But I've tried everything I found out and I can't solve it yet.

I've a .Net winforms app. It needs to connect to a SQL Server in a remote server in the same network. It works perfectlly in my machine, but it doesn't in antoher machine from my work. Both machines have Windows 7 and installed the SQL server, only client tools (the exactly same installation, I think).

I've read this article: http://blog.sqlauthority.com/2009/05/21/sql-server-fix-error-provider-named-pipes-provider-error-40-could-not-open-a-connection-to-sql-server-microsoft-sql-server-error/ . I'll tell you the result of each Solution:

1) "check if SQL Server service status is “Running” ". I've installed only SQL server client, "Sql Server servicies" list is empty.

"In addition, ensure that your remote server is in the same network. Run “sqlcmd -L” in your command prompt to ascertain if your server is included in your network list." It is included in servers list.

2) It is enabled in both machines.

3) There is no active Firewall in both machines.

4) It is enabled. Also, if it weren't be enabled my app woudn't work in any pc.

5) Again, I've installed only SQL server cliente. "Sql Server servicies" list is empty.

6) There is no active Firewall.

7) We are not using alias at all (any machine).

Please help!!

Thanks,

DIego

Answer 1

I don't see in your list if you checked whether or not remote connections are available. Use SQL Configuration Manager and make sure TCP/IP connections are allowed. Then restart your SQL service and retry from the remote machine. If you are using SQL Express remote connections are not allowed by default.

Answer 2

I've found out that in the machine wich didn't work, NOD32 antivirus didn't have completly disabled the firewall. Also after I did, I had to reboot to make it work.