We have a MS-Access front application using data from a SQL server back-end. We are using ODBC connections for the data communications. The application randomly getting frozen or crashes giving different errors as attached below which very likely seems to be issues related to ODBC connection. Problems can be recreated by running different queries in quick successions.
SQL Server Version: SQL Express 14.0.3356.20
Access Version: Microsoft 365 Apps for Business Version 2011 (Build 13426.20204)
Most common error codes:
10054, 10060, 3146, 3151
ODBC Data Source Type: System DSN
ODBC Driver: ODBC Driver 17 for SQL Server (Version 2017.176.01.01)
Example Connection String for a linked table: ODBC;Description=Test Description;DRIVER=ODBC Driver 17 for SQL Server;SERVER=MY-SERVER;UID=MyUser;Trusted_Connection=No;APP=Microsoft Office;DATABASE=TestDatabase;;TABLE=dbo.TableName
Largest Table Size: 53000 records (Doesn't really matter, fails for even smaller queries, but if you try faster getting results from different queries you can break it)
Error1 Error2 Error3
We have gone through hundres of searches/articles about these and applied the fixes listed below, but still couldn't get the problem solved.
We have tried below solutions as of now which didn't help.
Created firewall rules (Inbound - TCP Port 1433, Outbound - TCP all
ports)
Added TCP Port 1433 - TCP/IP protocol
Enabled Namepipe
Updated SQL Server Express from 14.0.3335.7 to 14.0.3356.20
Made IP4 and IP6 are both enabled
Enabled and checked ODBC Trace Logs
Checked Windows Event Logs
Hope I have included everything that might be useful to get some help resolving this issue.
Note: Not sure if it's related, but the SQL Server itself (in the backend) giving the below error in rare occasions if it helps.
Connection Timeout Expired. The timeout period elapsed while attempting to consume the pre-login handshake acknowledgement. This could be because the pre-login handshake failed or the server was unable to respond back in time. The duration spent while attempting to connect to this server was - [Pre-Login] initialization=29278; handshake=26244; (.Net SqlClient Data Provider)
Thanks everyone who tried to help. This issue has now been fixed.
For anyone who will come here in future looking for a solution for a similar issue, below is what worked for us.
Added a new instance of SQL Server 2019 (in the same virtual machine
which 2017 sits on)
Enabled UDP Port 1434
Changed virtual port from blank to zero
2017 was still crashing before taking offline with the same settings.
No issues with the 2019 version.
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 am having some connection pool issues in my sharepoint application. Every time that my application tries to fetch some data from an SQL Server 2008 R2, I got this exception:
"Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached."
I know that I am probably having connections leak problems, but I have checked all parts of my code that I am accessing the database, and all of them are implemented with the using() pattern. My SQL Server version is 2008 R2 Express, so I don't have the Profiler Tool to see how many connections my application is actually creating.
I have tried disable the pooling setting the Pooling=false; in my connection string, but I've got the same error. Also, I have tried increase the connection timeout and the max pool size with no success.
Inspecting the User Connections on my SQL Server instance before my application get failed using the perfmon, I have got that the number of connections is not even close to 100 (the default max pool size).
One important information is that if I run this application in another computer here in my office, it works perfectly.
Obs: I am using entity context to access the database and this application is not published, I am just run it locally with vs2013.
If you guys know some good way to inspect the connections behavior of my application or have a idea of what could be happening in my development environment, please share with me.
Thanks.
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 have a bunch of VB6 applications that access two different database servers (both 32-bit windows 2003, one SQL Server 2000, one SQL Server 2005). About every ten minutes or so, we are getting a few errors:
[Microsoft][ODBC SQL Server Driver]Timeout expired
[Microsoft][ODBC SQL Server Driver][DBNETLIB]SQL Server does not exist or access denied.
[Microsoft][ODBC SQL Server Driver]ConnectionRead()
This is happening on more than a dozen different computers at random times. We also have IP phones that all run through the same network and those are not having any problems. We can also VNC into a users computer and reproduce the error they were getting, but VNC still continues to work. Email also works. It just seems to be an ODBC connection to SQL Server that causes the issue. The errors happen for both of our SQL Servers. We have scoured google, but haven't been able to come up with a solution. Is there anything we can try to diagnose the problem? Is there any fix out there?
Update:
We have no internal firewalls on either the servers or clients. We connect through TCP/IP via the dns name of the server (also have tried IP address).
One server has Windows 2003 SP2 and the other doesn't.
The strange thing is that it has worked fine for years and now all of a sudden these errors are happening. Nothing has changed on those servers for quite some time. That leads us to beleive it is a bad switch, but that seems unlikely since nothing else (email, phones, vnc, file server, etc) all work without problems.
Take a look at this Microsoft Knowledge Base article.
Some problems occur after installing Windows Server 2003 SP2
I would also suggest that you switch to an OLE DB provider. In my experience, it's faster than ODBC and more reliable too.
Connection Strings
Scroll down to: SQL Native Client OLE DB Provider
Are you using non-default instances? Or do you have internal firewalls?
We changed to "server.fqdn.tld\instance,port" to avoid this exact (IIRC) intermittent connection issue from clients behind internal firewalls.
Only SQL connections were affected.
We never did figure out why this was happening. We upgraded our server to SQL Server 2008 and the error messages stopped.
I recently came across a very similar problem and posted it here.
ScottE found the solution.