I was working on an ASP.NET MVC5 application and pushed it to git. Someone else cloned the project to their computer.
When they try to run the app it works up until there is a database call. They get the error message:
System.Data.SqlClient.SqlException: '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: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)'
In the Server Explorer we can see that the connection is closed. We also see no tables at all, like as if there was no database.
Does anyone know how we can approach this? I'd think that the connection string remains the same on each machine? The database was created code first, do we somehow have to recreate it? If so, how?
Thanks for your suggestions!
The connection string should be the same.
You should first disable Windows Firewall and antivirus programs (and similars), if they're present, and test again.
You should try a connection via another database client too, just to check if you are blocked someway.
If these attempts doesn't solve the problem, you can recreate the database for test pourposes, if you will. For Entity Framework, for example, search "migrations" term in Google.
The error is relevant. Obviously, from the computer hosting the cloned solution, the SQL server is not reachable.
If, in development, you used a local SQL Server (like SQL Express or Local DB), you must verify that on the computer hosting the clone solution you have the same setup. If you used a remote server, you must check that the server is available to the computer hosting the cloned solution.
In both cases, you can use Server Explorer to verify the db connection and access.
Unfortunately, there is no satisfying answer.
At first, we reinstalled Microsoft SQL Server. That alone did not help.
We did change the autentication from Windows Authentication to SQL, because the person working on that workstation still had the account details from the previous owner.
That alone did make the test connection successful. But then, we got another error when doing the "Update-Database" command in VS, which we solved by deleting a rogue migration that was there for some reason unknown.
Now it works - sorry for not offering a more concise solution.
I have been using SSMS and LinqPad both for months to connect to SQL Azure instances without issue. Suddenly this week, linqpad stopped connecting, consistently timing out and displaying this error message: "A connection was successfully established with the server, but then an error occurred during the pre-login handshake. (provider: SSL Provider, error: 0 - the wait operation timed out.)"
At first, it was just LinqPad. But soon after I started experiencing the same issue with SSMS 2012. It showed the exact same error message (slightly different dialog).
I've confirmed that this isn't a firewall rule issue. My IP has been allowed through the SQL firewall for months, and I can still connect using the same credentials using SQLCMD and I can run queries.
Any ideas? Why would SSMS and LinqPad both take a big dump while SQLCMD still works?
I finally found the solution to this (I think I may have found it via https://stackoverflow.com/questions/13420770/pre-login-handshake-error-connecting-directly-to-sql-azure). I installed some completely unrelated software about the time that things stopped working. As it happens, said software also installs - silently - some bundled software that leaves you with custom Winsock LSPs in place, which means the system is then afflicted by an issue reported to Microsoft and addressed in KB 2568167. Fortunately, I didn't have to manually remove the LSPs because I was able to uninstall the unwelcome software (Sendori!).
Did you look at the connectivity troubleshooting guide for SQL Azure?
http://social.technet.microsoft.com/wiki/contents/articles/1719.windows-azure-sql-database-connectivity-troubleshooting-guide.aspx
Have you also installed .NET 4.5 recently/in that week time frame? Have you checked your SQL Connection to make sure that SSL encryption is off?
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.
First off, I don't know if this is possible, but let me describe my scenario.
I have a set of WCF services, a SQL Server 2008 Database all running on Windows Server 2008. All of this works fine when I am connected to my LAN, however I am going to be using this box for a demo, and I would like to make it work in standalone mode (ie, not connected to any network).
When I attempt to do this in standalone mode, the SQL Server database appears to be working (I am able to retrieve data). However when I try and insert data within a transaction scope from the WCF services, on the client side I am getting a communication fault exception. Checking the windows event logs, I see that there is a message along the lines of "MSDTC encountered an error while attempting to establish a secure connection with system ".
Does anyone know what needs to be set on the DTC to allow this to work
In context of what happened, the error now makes perfect sense.
The problem here was that somewhere in one of the applications deployed to the server, we were referring to a hardcoded dns name that was inaccessible by this server (since it was standalone). From what I understand, the DTC attempted to flow the transaction, failed to establish the address from the computer name and that was where it bombed out. As the application was a WCF service, the error was pretty well obfuscated, but eventually we traced by turning on service tracing.
Hope that helps anyone else that encounters a similar error. Beware the hardcoded values.
It could be to do with the connection string the WCF services use to connect to the database. Try using Data Source=. or Data Source=localhost, to ensure you are using the loopback network adapter (127.0.0.1).
Is there a firewall running on the Windows machine? Is the server part of a domain?
I would also suggest looking at the security settings dialog of MS DTC (Component Services MMC plugin). Try setting the "Transaction Manager Communication" to "No Authentication Required" and ticking most other options as a base line.
Greetings – To automate testing of our database SPROCs, we’ve been using dynamically created databases inside of a User Instance. This has been working very well – the build server and, until very recently, all the developers could all run the tests. However, one of our developer machines is now returning the following error when we try to connect to the user instance:
Failed to generate a user instance of
SQL Server due to a failure in
starting the process for the user
instance. The connection will be
closed.
Here is what the log file says:
2008-12-04 10:46:29.77 Logon
Error: 15372, Severity: 16, State: 1.
2008-12-04 10:46:29.77 Logon
Failed to generate a user instance of
SQL Server due to a failure in
starting the process for the user
instance. The connection will be
closed. [CLIENT: ]
What I’ve done to fix it so far
Deleted C:\Documents and Settings[username]\Local Settings\Application Data\Microsoft\Microsoft SQL Server Data
Changed SQL Service to run as “Local System” instead of “Network Service”
Uninstalled SQL Express, deleted ALL data directories (e.g. “MSSQL.1”), and reinstalled SQL Express
None of these “fixes” have fixed the problem. It used to work on the machine in question, and we would like not to have to repave it.
Please help!!!
Thanks - Jordan
Okay, I tried all of the above fixes again, and then I restarted the entire system and it appears to work. Strange! I had restarted my system in the past, but it looks like you have to apply these fixes first and then restart. I think I'll try switching the service back to logging in as Network Service.
Thanks - Jordan
I found the same issue on my azure VM. Then I opened the SQL Server Configuration Manager, opened SQL Server Network Configuration, -Protocols for and found that "Named Pipes" and "TCP/IP" were disabled. I enabled them, and the error went away.