问题
I just installed SQL Server Express 2012 on my home server. I\'m trying to connect to it from Visual Studio 2012 from my desktop PC, and repeatedly getting the well-known error:
A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)
What I\'ve done to try to fix this:
- Run SQL Server Configuration Manager on the server and enable SQL Server Browser
- Add a Windows Firewall exception on the server for TCP, ports 1433 and 1434 on the local subnet.
- Verify that I have a login on the SQL Server instance for the user I\'m logged in as on the desktop.
- Verify that I\'m using Windows Authentication on the SQL Server instance.
- Repeatedly restart SQL Server and the whole dang server.
- Pull all my hair out.
How can I get SQL Server 2012 Express to allow remote connections!?
回答1:
Well, glad I asked. The solution I finally discovered was here:
How do I configure SQL Server Express to allow remote tcp/ip connections on port 1433?
- Run SQL Server Configuration Manager.
- Go to SQL Server Network Configuration > Protocols for SQLEXPRESS.
- Make sure TCP/IP is enabled.
So far, so good, and entirely expected. But then:
- Right-click on TCP/IP and select Properties.
- Verify that, under IP2, the IP Address is set to the computer's IP address on the local subnet.
- Scroll down to IPAll.
- Make sure that TCP Dynamic Ports is blank. (Mine was set to some 5-digit port number.)
- Make sure that TCP Port is set to 1433. (Mine was blank.)
(Also, if you follow these steps, it's not necessary to enable SQL Server Browser, and you only need to allow port 1433, not 1434.)
These extra five steps are something I can't remember ever having had to do in a previous version of SQL Server, Express or otherwise. They appear to have been necessary because I'm using a named instance (myservername\SQLEXPRESS) on the server instead of a default instance. See here:
Configure a Server to Listen on a Specific TCP Port (SQL Server Configuration Manager)
回答2:
The correct way to connect to remote SQL Server (without opening UDP port 1434 and enabling SQL Server Browser) is to use ip and port instead of named instance.
Using ip and port instead of named instance is also safer, as it reduces the attack surface area.
Perhaps 2 pictures speak 2000 words...
This method uses the specified port (this is what most people want I believe)..
This method requires opening UDP port 1434 and SQL Server Browser running..
回答3:
One More Thing...
Kyralessa provides great information but I have one other thing to add where I was stumped even after this article.
Under SQL Server Network Configuration > Protocols for Server > TCP/IP Enabled. Right Click TCP/IP and choose properties. Under the IP Addresses you need to set Enabled to Yes for each connection type that you are using.
回答4:
You can use this to solve this issue:
Go to START > EXECUTE, and run CLICONFG.EXE.
The Named Pipes protocol will be first in the list.Demote it, and promote TCP/IP.
Test the application thoroughly.
I hope this help.
回答5:
You can also set
Listen All to NO
in the protocol dialog then in the IP address IP1 (say)
set enabled to Yes,
define yr IP address,
set TCP Dynamic to Blank and
TCP port to 1433 (or whatever)
回答6:
This article helped me...
How to enable remote connections in SQL Server
Everything in SQL Server was configured, my issue was the firewall was blocking port 1433
回答7:
I had this problem recently. 2015 Aug
Solved by opening SQL Server Configuration Manager
- SQL Server Network Configuration -> Protocols for SQLEXPRESS
- Properties on TCP/IP -> IP Adresses tab
- Everything stays default, only set IPALL: TCP Port to 1433
Can connect to with SQL Server Manager to machine: [hostaddress], 1433
Example:
回答8:
On my installation of SQL Server 2012 Developer Edition, installed with default settings, I just had to load the SQL Server Configuration Manager -> SQL Server Network Configuration -> Protocols for MSSQLSERVER and change TCP/IP from Disabled to Enabled.
回答9:
I had to add a firewall inbound port rule to open UDP port 1434. This is the one Sql Server Browser listens on.
回答10:
I prefer way of "Rosdi Kasim" as that's doesn't require detail configuration on the IP.
I will definitely forget it again when I try to up another server again.
Keep It Simple Stupid (KISS) by simply enable the Sql Server Browser service, then add the \SQLEXPRESS behind the IP when you connect the server.
Direct using IP without "\SQLEXPRESS" was my point of failure as it doesn't use the default port.
Thanks.
回答11:
I had the same issue with SQL Server 2014 locally installed named instance. Connecting using the FQDN\InstanceName would fail, while connecting using only my hostname\InstanceName worked. For example: connecting using mycomputername\sql2014 worked, but using mycomputername.mydomain.org\sql2014 did not. DNS resolved correctly, TCP/IP was enabled within SQL Configuration Manager, Windows Firewall rules added (and then turned the firewall off for testing to ensure it wasn't blocking anything), but none of those fixed the problem.
Finally, I had to start the "SQL Server Browser" service on the SQL Server and that fixed the connectivity issue.
I had never realized that the SQL Server Browser service actually assisted the SQL Server in making connections; I was under the impression that it simply helped populate the dropdowns when you clicked "browse for more" servers to connect to, but it actually helps align client requests with the correct port # to use, if the port # is not explicitly assigned (similar to how website bindings help alleviate the same issue on an IIS web server that hosts multiple websites).
This connect item is what gave me the clue about the SQL Server Browser service: https://connect.microsoft.com/SQLServer/feedback/details/589901/unable-to-connect-on-localhost-using-fqdn-machine-name
- when you use wstst05\sqlexpress as a server name, the client code separates the machine name from the instance name and the wstst05 is compared against the netbios name. I see no problem for them to match and the connection is considered local. From there, we retrieve the needed information WITHOUT contacting SQL Browser and connect to the SQL instance via Shared Memory without any problem.
- when you use wstst05.capatest.local\sqlexpress, the client code fails the comparison of the name (wstst05.capatest.local) to the netbios name (wstst05) and considers the connection "remote". This is by design and we will definitely consider improving this in the future. Anyway, due to considering the connection remote and the fact that it is a named instance, client decides that it needs to use SQLBrowser for name resolution. It attempts to contact SQL Browser on wstst05.capatest.local (UDP port 1434) and apparently that part fails. Hence the error you get.
The reason for the "SQL Server Browser" service from TechNet (emphasis added by me): https://technet.microsoft.com/en-us/library/ms181087(v=sql.120).aspx
From the "Using SQL Server Browser" section:
If the SQL Server Browser service is not running, you are still able to connect to SQL Server if you provide the correct port number or named pipe. For instance, you can connect to the default instance of SQL Server with TCP/IP if it is running on port 1433. However, if the SQL Server Browser service is not running, the following connections do not work:
- Any component that tries to connect to a named instance without fully specifying all the parameters (such as the TCP/IP port or named pipe).
- Any component that generates or passes server\instance information that could later be used by other components to reconnect.
- Connecting to a named instance without providing the port number or pipe.
- DAC to a named instance or the default instance if not using TCP/IP port 1433.
- The OLAP redirector service.
- Enumerating servers in SQL Server Management Studio, Enterprise Manager, or Query Analyzer.
If you are using SQL Server in a client-server scenario (for example, when your application is accessing SQL Server across a network), if you stop or disable the SQL Server Browser service, you must assign a specific port number to each instance and write your client application code to always use that port number. This approach has the following problems:
- You must update and maintain client application code to ensure it is connecting to the proper port.
- The port you choose for each instance may be used by another service or application on the server, causing the instance of SQL Server to be unavailable.
And more info from the same article from the "How SQL Server Browser Works" section:
Because only one instance of SQL Server can use a port or pipe, different port numbers and pipe names are assigned for named instances, including SQL Server Express. By default, when enabled, both named instances and SQL Server Express are configured to use dynamic ports, that is, an available port is assigned when SQL Server starts. If you want, a specific port can be assigned to an instance of SQL Server. When connecting, clients can specify a specific port; but if the port is dynamically assigned, the port number can change anytime SQL Server is restarted, so the correct port number is unknown to the client. ... When SQL Server clients request SQL Server resources, the client network library sends a UDP message to the server using port 1434. SQL Server Browser responds with the TCP/IP port or named pipe of the requested instance. The network library on the client application then completes the connection by sending a request to the server using the port or named pipe of the desired instance
回答12:
I had to add port via Configuration Manager and add the port number in my sql connection [host]\[db instance name],1433
Note the , (comma) between instancename and port
回答13:
I had a different problem from what all of the answers so far mentioned!
I should start off by saying that I had it in Visual Studio, and not SQL Server Express but the solution should be exactly the same.
Well, god, it's actually really simple and maybe a bit foolish. When I tried to create a database and Visual Studio suggested the name of the SQL Server it gave me my Windows username and since it's actually the name of the server I went for it.
In reality it actually was my Windows username + \SQLEXPRESS. If you didn't change any settings this is probably yours too. If it works, stop reading; this is my answer. If it doesn't work maybe the name is different.
If, like me, you only had this problem in Visual Studio to check what is yours follow these steps:
- Open SQL Server Management Studioicon.
- If you don't see your server (docked to the left by default) press F8 or go to View -> Object Explorer.
- Right click on the name of the server and choose Properties (The last item)
- At the bottom left you can see your server's actual name under "Server" (not Connection, but above it).
This is the name of the server and this is what you should attempt to connect to! not what Visual Studio suggests!
回答14:
One more thing to check is that you have spelled the named instance correctly!
This article is very helpful in troubleshooting connection problems: How to Troubleshoot Connecting to the SQL Server Database Engine
回答15:
In my case the database was running on non standard port. Check that the port you are connecting is the same as the port the database is running on. If there are more instances of SQL server, check the correct one.
回答16:
All you need to do is open the relevant port on the server's firewall.
回答17:
Having problems connecting to SQL Server?
Try disconnecting firewall.
If you can connect with firewall disconnected, may be you miss some input rules like "sql service broker", add this input rules to your firewall:
"SQL ADMIN CONNECTION" TCP PORT 1434
"SQL ADMIN CONNECTION" UDP PORT 1434
"SQL ANALYSIS SERVICE" TCP PORT 2383
"SQL BROWSE ANALYSIS SERVICE" TCP PORT 2382
"SQL DEBUGGER/RPC" TCP PORT 135
"SQL SERVER" TCP PORT 1433 and others if you have dinamic ports
"SQL SERVICE BROKER" TCP PORT 4022
来源：https://stackoverflow.com/questions/11278114/enable-remote-connections-for-sql-server-express-2012