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.
Related
I'm running into a frustrating problem with a subset of users. I've got a small client application that runs on their local machine and throws an error when trying to connect to a remote database server.
Here's the error and what I know:
[DBNETLIB]SQL Server does not exist or access denied
There are lots and lots of other instances of this I've searched through, but all of the ones I've found point to a server-side issue (not running, firewall blocking port 1433, etc.). In my case, the problem is only occurring on a subset of users systems, so I have to assume it is something specific to their systems.
Credentials for the SQL Server are using a service account, so it's the same for all users, ruling out some users being properly set up but not others
When the error occurs, the response takes a long time to come back, which would lead me to think that the error is related to a timeout and not denied access (this might be a bad assumption)
The error occurs no matter whether I use OleDBConnection or ODBCConnection
The error occurs if I use a connection string built on the fly or a DSN I created. The DSN points to the same SQL server that I can't connect to via my application and uses the same {SQL Server} driver. I've also tried it using the SQL server native client 11 and get the same issue.
I can create a user DSN on their machine and successfully test the connection to the server with it
I can use the user DSN to link a table on the remote server in a Microsoft Access database on their machine and that works.
I compiled my code 64 bit only as well as trying 32 bit to see if anything helped. It did not.
I'd assume it has to be something in my code, except it works for multiple other users. So some combo of my code plus their system configuration has to be at play, right?
Here's the entirety of the connection logic:
dim DBConnection as OdbcConnection = New OdbcConnection()
DBConnection.ConnectionString = "DSN=<DSN name>;Uid=<username>;Pwd=<password>"
DBConnection.Open()
It times out on the DBConnection.Open(). I looked at the ODBC trace logs comparing my own system's trace to theirs, and it looks identical up until the point where I get a successful connection back and they get a timeout.
Any thoughts? I'm stumped.
Your point #1 is most likely the cause (port 1433 is blocked), but this is on the client side, not the server. Chances are, they are running firewall software (such as Windows Firewall) that is blocking outbound SQL Server connections.
If it's Windows Firewall, there is a built-in wizard that will allow you to allow outbound SQL Server connections.
Regarding this:
When the error occurs, the response takes a long time to come back, which would lead me to think that the error is related to a timeout and not denied access (this might be a bad assumption)
When the server address can't be found or can't be connected to, most of the time, the client will take a while before throwing the "connection" error. It won't throw the error immediately.
Other possibilities:
VPN
Server name vs IP address - I've had users that could NOT ever connect to a SQL Server box using the server name, because of various network configuration issues, either on their devices or because of network configurations at their location. Try using the IP address (or vice versa).
I have a SQL Database in Azure. Multiple ones actually. I am a global admin and have created some of the databases and another developer created the others. All of a sudden when I try to connect to them using the admin account that was created when the databases where created, I am getting the following exceptions:
Error connecting to '<DATABASENAME (I replaced the text here.)>'.
Failed to retrieve data for this request. (Microsoft.SqlServer.Management.Sdk.Sfc)
An exception occurred while executing a Transact-SQL statement or batch. (Microsoft.SqlServer.ConnectionInfo)
A transport-level error has occurred when receiving results from the server. (provider: TCP Provider, error: 0 - An existing connection was forcibly closed by the remote host.) (.Net SqlClient Data Provider)
That is from SSMS. If I try the same thing in Azure Data Studio, I connect to the database, but trying to view the tables throws an exception.
An exception occurred while executing a Transact-SQL statement or batch.
Also, all my connection strings in C# code work using the same account to perform CRUD operations. So it appears that I am connecting the server, but when trying to get the metadata for the database it's failing. I have not changed any firewall setting, I use the built in antivirus in windows 10. I have made sure that the white-listed IP in Azure is in-fact mine and it hasn't changed. I have been googling the heck out of this all weekend and can't find a cause of solution. I hope the issue I am having makes sense. Thank you in advance for any help you can provide.
Check if in Azure settings there is a rule to grant at your machine access on DB hosted in Azure space.
You can go here, a guide about Azure firewall rule.
I have found out that something on my laptop is corrupt. When I ran SSMS on another laptop on the same network, it worked fine. Also running SSMS in a VM on my laptop it worked. So something is corrupt. Just hard to find what it is, since I already uninstalled/installed. So I will be wiping machine and starting from scratch.
The issue ended up being hard ware related on my machine. I have replace my computer and everything is working as it should.
I have read a number of articles on how to configure mirroring on SQL Server 2012. I went through the steps and everything worked until hitting the final step, which didn't work.
When I run this on the Principal:
ALTER DATABASE MyDBName SET PARTNER = 'TCP://1.2.3.4:5022';
I get this error:
The server network address "TCP://1.2.3.4:5022" can not be
reached or does not exist.
When I run the counterpart ALTER statement shown above, but on the Mirror, it works fine.
I have tried all the steps in this troubleshooting article.
Important points:
The Primary and Mirror servers are in different datacenters, not on the same network at all. Not connected by VPN. Completely untrusted by each other.
I can connect to the Mirror via SSMS on the Primary and run queries. And vice versa.
I configured certificates on each server to establish the trust relationship. Everything worked during the setup and config, no errors.
I configured the endpoints on both servers and verified they're active/enabled.
I opened port 5022 on both servers by configuring incoming and outgoing windows firewall rules. I can telnet to the Mirror from the Principal and vice versa - ports appear open, no problems.
In the troubleshooting guide mentioned above, I tried steps 1-6. I didn't try 7, deleting the endpoints and re-creating, because they look perfectly valid and active to me.
Looking for some ideas on this one.
If you can telnet that port from the principal machine everything is fine with TCP/IP and firewall settings.
I can remember that I had a similar issue in the past. Unfortunatly I dont remember the exact solution but it was related to security/authentication of the endpoints and the SQL Server service account not having enough permission on the mirror machine. Unfortunatly the error message is pretty misleading in this case. Script the endpoints and verify their settings, SSMS has no UI for that.
Another thing that you could check is that you have the possibility to also connect to port 5022 from the mirror to the principal machine. You will get the same error message if the connection is not possible from both instances.
Sorry that I cant provide you a proper solution, but maybe that points you to the right direction.
Unfortunately there are quite non-informative error messages in MS SQL. The problem might be an authorization issue and the server still will be saying "network address can not be reached".
Considering "servers are in different datacenters", how the authentication is performed? A MSSQL service (on server1) itself must be runned as a valid db user (on server2, and vice versa) in order to make the mirroring work.
There can be multiple reasons for this to happen.
In your SQL Server Management Studio, if you see a White bubble next to the server instance name, instead of the Green bubble, then you can try the following:
"Allow an app through firewall" and add "Windows Management Instrumentation (WMI)" for Windows Server 2012. If it is Windows Server 2008, you can allow "Remote Administration" through firewall.
Is it meant to be a semi colon?
ALTER DATABASE MyDBName SET PARTNER = 'TCP://1.2.3.4;5022'
The semi colon is used when connecting to IP / Port when using management studio.
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.
I just setup a new Windows Server 2008 machine with an instance of SQL Server 2008 Express. The SQL Browser service does not appear to be working correctly. In Management Studio, browsing for servers shows the hostname of the new server, but not the instance name. When you choose the hostname form the list it doesn't connect. But I can connect manually by typing the hostname\instancename combination.
update 1:
The browser service is running, and I have tried it with several different accounts, including domain administrator which is a bad practice, but I tried anyway for troubleshooting purposes.
I have tried punching the appropriate holes in the firewall, and also completely turning the firewall off.
This is running on a Hyper-V, Windows Server 2008 32 bit guest, which is on a Windows Server 2008 64-bit host. I have done this before (without issues) on this same host, but with SQL 2008 Standard instead of Express.
When I browse for the server in SSMS(Express) on the SQL Server machine, it works fine and shows the whole instance name. When I browse for it on a remote machine (on the same intranet) with SSMS (standard) it just shows the host name.
update 2:
Followed the packets as suggested and found the following
The client sent the broadcast as expected and received correct responses from other SQL Servers on the same network.
The server received the broadcast but did not send a response.
Considering these results, I wonder why the host name ever appears in the client list in the first place. It shouldn't show up at all, right?
update 3:
Spent an hour and a half on the phone with Microsoft support. I learned a few things, but the problem is not yet solved. It was suggested that I try installing an instance of SQL Standard on the same machine. I did that and the new instance exhibits all the same symptoms. The hostname shows up in the browse list only once, not once for each instance.
update 4:
Stackoverflow chose an answer for me thanks to the bounty system, but this question is not answered. Today I tried moving the whole VM to a different host server - everything is exactly the same. The hostname still appears in the browse list, without the instance name.
update 5:
Confirmed that Hyper-V Integration Services are installed on the guest (SQL) server.
check that the browser service is running, it's not turned on by default.
UPDATE1: See if you can install Network Monitor/Wireshark to do a network trace on the SQL Server to see if it's receiving the broadcasts and sending responses. I think this is your best option in troubleshooting this issue. According to MSDN the service uses UDP port 1434, so this is the traffic to watch.
UPDATE2: Does the server have multiple IP's? according to this MSDN article the Windows Server 2008 firewall has issues responding to SQL Browser service broadcasts, even with rules allowing packets through.
I tend not to rely on browsing. You'll get inconsistent results because browsing sends out a broadcast udp/1434 packet and waits for responses back. However, since you are able to connect remotely via SERVERNAME\INSTANCENAME, that aspect of the SQL Browser service is working. If it wasn't, you wouldn't have been able to connect. With that said, to troubleshoot the browsing portion:
Have you tried stopping and restarting the SQL Browser Service?
Have you tried stopping and restarting the instance if that didn't work?
To completely troubleshoot this, unfortunately, you'd have to do packet traces.
Sounds like the browsing service is messed up somehow...
I don't know if you can temporarily take this SQL Server down temporarily. But if so, you may want to try this:
Uninstall all SQL\instances completely.
Run the install of SQL Express 2008
Create a default instance during install (Not a named instance)
Run the installer again and create the default named instance (SQLExpress)
Try connecting to the named instance again. If it works, you can remove the default instance.
I had the same issue in a VM. After shutting down the Firewall it worked.
I just had this same issue. I was not able to see Instance Names in the SSMS Network Servers tab. It turned out that I had set up Hyper-V and created an Internal Network on my local machine. That network was identified as a Public/Guest Network and the Windows Firewall was ENABLED for it, even though my Domain setting has the Firewall DISABLED. Once I disabled that guest network on my computer I could see all the instances.
Machines:
Physical SQL Server 2014 Ent
Windows 8.1 laptop running Hyper-V