So we have SQL Server 2008 R2 Express running on a local server, and a bunch of machines on the same LAN use a program I wrote in C# to access said server.
All the machines in the building except one can connect quite happily.
Connection string is:
Data Source=[IP address here],53535\SQLEXPRESS;Initial Catalog=EMS_Main;;User ID=EMSUser;Password=[password here];
Exact error message is:
"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: TCP Provider, error: 0 - An invalid argument was supplied.)"
Struggling to believe the 'invalid argument' bit, given that all other machines connect quite happily.
SQSL is definitely configured to accept remote connections, instance name is definitely correct.
The problem machine can connect using SQLSMS, but not via C#.
Disabling firewall on the problem machine makes no difference.
Everything seems to have been working fine on the problem machine up until a Windows 10 update a couple of days ago.
EDIT: An update on this: I now have two machines with this issue, and they both seem to have only developed it after Windows 10 updated to version 1803. All the pre-1803 machines still work fine.
Can anyone shed any more light on this please?
For anyone else hitting this issue, I discovered that this was happening because the client application was being run from a shared drive, and Windows 10 update 1803 must have some security update in it that causes this problem (only machines running 1803 were affected).
Running the application from the machine's hard drive solved the problem.
I'd still like to know a technical explanation for this, even though the problem is solved.
I have the same issue. A dig deeper and discovered that this happened after installing an update (May 8, 2018—KB4103721). Try to uninstall this update or use named pipes instead tcp.
I have an old VB6 application that establishes a connection to the SQL Server and uses it throughout the lifetime of the application.
We recently upgraded the back end to SQL Server 2016 (from 2005) and noticed an odd issue. If the user leaves the application idle for several hours, and then tries to do anything having to do with the database, they get run-time error -2147219450 (80040806) or Connection Failure. The application does check the ADODB.Connection.State and it always reports that the connection is open. We are seeing this error pretty consistently on multiple, pretty diverse (in terms of OS versions) workstations.
I haven't seen anything on Google relating to this. Can someone shed some light on this issue?
I was getting this issue with this driver only when connecting to sqlserver instance on my local machine. Seemed like there was a bug in the shared memory client protocol. Switching to TCP for local connections (Turning off shared mem and named pipes) solved the problem.
the error i was getting was
Microsoft OLE DB Provider for SQL Server "Connection failure" SQL State: 08S01
Yes folks, it's this one again.
"A connection was successfully established with the server, but then
an error occurred during the login process (provider: TCP Provider,
error: 0 - An existing connection was forcibly closed by the remote
host.)"
I'm sorry... I have Google'd this, I have read the other StackOverflow articles on this problem, and I have tried all kinds of suggestions, but nothing works.
Here's a few notes about what we're seeing.
This issue occurs occassionally in SQL Server Management Studio itself (doing any kind of database activity... getting a list of tables in a database, having a look at a Stored Procedure, etc)
It also happens in Visual Studio 2010 itself, when it is trying to get data from the servers (e.g. when creating a .dbml file, etc)
It also sometimes happens in our .Net (ASP, WPF, Silverlight) applications.
Our SQL Server 2005 & 2008 servers are all based on virtual machines in data centres around the world, and we see sometimes this error on each of them. But most of the time, they all work absolutely fine.
When the error does occur, we can just "retry" what caused the error, and then it'll work fine.
We think.. if we have an IIS Web Server in a data centre in a particular city, and it accesses a SQL Server in the same data centre, then we don't see the issue.
We think.. if we connect to the servers, and specify the UserID and Password to use, it causes this error much more frequently than if we just use Active Directory authentication.
Put all that together, and it sounds to me like some kind of network issue.
But can anyone suggest what to look for ?
This isn't a bug in our .Net applications, as even SQL Server Management Studio "trips up" with this error.
It's baffling us.
Just in case anyone else hits this issue, we finally found the solution.
Our company uses Riverbed software to compress data, when it's being passed between locations, and this was somehow causing some connections to get dropped.
Our IT gurus found a configuration setting which finally fixed this issue.
I believe there's a setting in there to turn off compressing results from SQL Server (or something like that). That fixed it for us.
It could be any number of network issues. ANYTHING that prevents the code from reaching the server even for the few miliseconds it takes to make one query.
it could also be the result of a failover. When we went from a single SQL Server to a clustered environment, we'd see this happen during a failover. In this case, it turned out to be our Connection Pooling. In essence, the SQL cluster has a controller and two servers behind it. A and B.
Say our web app is using server A just fine, Connection pooling creates a connection on both sides. The server is aware of it, and the web app is aware of it. Once the cluster fails over to the second server, the web app is aware of the connection but server B is not, so we get an error.
The point is, any possible cause of network issues imaginable may be the cause. DOS attacks on the server, man-in-the middle attacks intercepting and changing traffic. Someone trips on an ethernet cable and it's loose in the jack. You name it, if it can cause a connection issue, it could be the cause.
Your issue also sounds like one we had recently - we also have a virtual environment, wih software that moves VMs from one host to another as needed for load balancing. Every so often, we'd get bombarded with the same error. It turned out to be an issue with the NIC drivers on one of the hosts, so whenever a VM moved to that particular host, errors would occur.
It's really not a programming issue. It's an environment issue, and you need trained professionals with direct access to your environment to research and resolve this.
My problem was that I was inadvertently using a wireless network to connect to our network because the Ethernet cable was faulty. This after repairing SQL Server, running a Winsock reset as recommended elsewhere ...
I am experiencing the same issue and our app interfaces with a several Azure SQL DBs. I believe (same as you) I do not have a bug in the C# code to cause this issue. We've solved it by a simple for loop containing an extra attempts to try to connect to the Azure SQL again if the previous attempt fails and then run the query.
Most of the time everything runs fine but sometimes we can see the loop kicked-in and on the 2nd or 3rd time it executed properly without the below mentioned error. After that we see in the log file the error below for all the unsuccessful attempts:
A connection was successfully established with the server,
but then an error occurred during the login process. (provider: TCP
Provider, error: 0 - An existing connection was forcibly closed by the
remote host.)
Even though this is a less-then-pretty solution, it allowed us to run our app without interruptions. I know you've mentioned that trying to connect again (to introduce some connection-failure tolerance) solves the problem and unfortunately this is the only correct solution I found so far as well.
I should mention that we have tried many debugging strategies to figure this out. Right now it all points to the availability of the database we are trying to connect to i.e.: It happens if the number of allowed DB connections is exceeded. (or so it seems at this time)
Turn off your VPN
My Problem fixed by turn off VPN
It was happening in our code when we were opening the dbconnection for oracle and were passing DBtype as SQL in our database object.
in my case - the error was Microsoft first suggestion:
Client is connecting with an unsupported version of the SQL Server Native Client.
In our case, We got this error when we updated sql server to sp3. We were not able to connect to the database from SSIS package.
We updated the native client and configurations. We were able to connect.
link to download the native client - https://www.microsoft.com/en-us/download/confirmation.aspx?id=50402
Link for configurations settings and further troubleshooting - https://learn.microsoft.com/en-us/previous-versions/sql/sql-server-2008-r2/ms187005(v=sql.105)
Hope it helps.
Cheers!
Had the same type of issue. In my case it was a bit more complicated... I could connect to “ServerA” from “ServerB” via SSMS, but it would fail with sqlcmd. The error was the same:
Sqlcmd: Error: Microsoft SQL Server Native Client 11.0 : TCP Provider: An existing connection was forcibly closed by the remote host.
I could also connect from “ServerC” with both SSMS and sqlcmd. The following are the versions on the VMs:
ServerA: Microsoft Windows Server 2012 R2 Datacenter / Microsoft SQL Server 2012 (SP3-CU10) (KB4025925) - 11.0.6607.3 (X64)
ServerB: Microsoft Windows Server 2012 R2 Datacenter / Microsoft SQL Server 2012 - 11.0.5058.0 (X64)
ServerC: Microsoft Windows Server 2012 R2 Datacenter / Microsoft SQL Server 2012 (SP3-CU10) (KB4025925) - 11.0.6607.3 (X64)
Bottom line was the “unsupported version”. I noticed a mismatch of “sqlncli11.dll” between ServerC and ServerB, so I copied it to the System32 folder. After this, sqlcmd worked like a charm. Below were the versions in my case:
Failed:
FileVersion: 2011.0110.5058.00
ProductVersion: 11.0.5058.0
Worked:
FileVersion: 2011.0110.6607.03
ProductVersion: 11.0.6607.3
I was working on 2 projects at the same time (on 2 different machines) and both used SQL Server.
When i disconnected SQL with 1 machine the errorMessage went away. Probably you can mess around with IP-adresses too to fix the problem.
In my case I was seeing this error intermittently from a .Net application connecting to a SQL server located in the same server room. It turned out that some of the databases had auto close turned on which caused the server to close the connections in the pool. When the application tried to use one of the pool connections that had been closed, it would throw this error and I saw a log message on the SQL server that the database it was trying to connect to was being started. Auto-close has now been turned off on those databases and the error hasn't been seen since.
Also, having auto-close on is the default behavior for SQL Express databases and these were originally created on an Express instance during testing before being migrated to the production server where we were seeing the errors.
this answer is for those how have this problem with Azure Sql server database.
It happens when you reach mat pool
first remove Persist Security Info=False from connection string
second check your database plan in azure portal and increase the PTUs of your database plan.
In SSMS "Connect to Server" screen click Options, then on "Connection Properties" TAB change "Network protocol" to "Named Pipes"
Try this -
Click Start, point to All Programs, and click SQL Server Configuration Manager.
Click to expand SQL Server Network Configuration and then click Client Protocols.
Right-click the TCP/IP protocol and then click Enable.
Right-click the Named Pipes protocol and then click Enable.
Restart the SQL server service if prompted to do so.
I have had this issue a couple of time already, and I've fixed by reducing the MTU size. Often 1350, 1250, etc on my network interface.
We've been experiencing a strange issue with SQL 2008 R2 (10.50.1600) installed as a named instance. In order for any external clients to connect, we have a certain procedure we have to follow, but should not have to. Now I did in fact open the TCP/IP and Named Pipes protocols on the SQL server and restarted it, this isn't the problem. We're on an Active Directory Domain (running from Server 2003). The problem exists no matter what OS the server or client is (XP, 2003, 2008, Vista, 7, 64bit, 32bit, etc.). The problem also persists from anything which can connect, for example, SQL Management Studio, ADO (from our applications), etc.
The problem is that before any client can connect to this server, each client machine must first connect to this server through ODBC (and we don't use ODBC). Any attempt to connect to a 10.5 SQL server before doing this results in "Server does not exist or access denied". But once we can connect in the ODBC (through Named Pipes), then everything else starts to work. The same issue occurs both when using the Computer Name and IP Address. In fact, if we want to connect with computer name \ instance name, then we have to do so first in the ODBC, and then if we want to connect via the IP address \ instance name, then we have to do the same also for that.
We've been having to do this on every single client computer. Again, once the ODBC is able to connect to this SQL server through Named Pipes, then all future attempts from that client work.
What could be causing this to occur? How to avoid it? I should not have to do this "ODBC Trick" as we've been calling it. I've never had this issue on any other version of SQL.
The issue might be related to the SQL Browser service. Each sql instance will have a different port number - try connecting from the client as IP Address,Port (e.g. 123.123.123.1,1433) - this will exclude DNS and Browser from the equation
Edit: now knowing that it is browser related, try see why clients can't access SQL Browser (usually Port 1434). Service not started? Possibly firewall blocking?
Microsoft have tied down everything security wise now by default, so any new configuration now generally requires quite a bit of detailed security planning, policy configuration, permissions etc. Welcome to the age of non-trust ;)
You could easily test your connection by creating a simple file. Follow the steps here at "How to test an SQL Server connection": http://teusje.wordpress.com/2012/02/21/how-to-test-an-sql-server-connection/
I am getting an error while connecting sql express server 2005 over the network.
An error has occurred while establishing a connection to the server. When connecting to SQL Server 2005, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections.
I have tried following things.
1. Allow remote connection along with both TCP and named pipe checked in both (target and initiator machine) in surface configuration manager.
2. sql browser is on automatic mode and running on both the machines.
Still I am not able to connect to machine.
I could see the server name (without "/sqlexpress") with the list but not able to connect.
I think if it could start showing TargetServer/sqlexpress then I could connect it easily.
Please guide me if I am missing anything.
Thanks in advance.
Anil
This is a pretty common problem, because by default, the remote support is turned off, and firewalling is enabled, so turning on the service doesn't always open the port.
Have a look at the answer to this MSDN question
Also check the authentication method - this is usually my problem. Eg. Windows Authentication across OS types or different usernames.