I maintain a system of automated data processing machines which run processes written in C# that are controlled by an SQl Server 2014 Enterprise Edition Database. Several times a day all of the processes on one machine will start receiving the following error:
An error has occurred. Details of the exception: 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) Unable to connect to SQL Server database.
All processes on the machine will experienc the same error when attempting to contact the database. After 10 or 15 minutes the machine will be able to connect again. While this is happening other machines on the same network will be able to connect no problem. We have checked the database - SQL Server is running - it is not blocked it is accepting connection, the instance name is correct. This is an intermittant problem that does not affect all machines connecting to the database but when it affects one - all processes experience the error. I have searched on this message and all the answers I have found are for constant failures - not intermittant like I am experiencing.
UPDATE
Found this on another question - Am testing now looks good:
The problem was that SQL was configured to allow both TCP and Named Pipes. Sometimes it would try and connect with the latter which doesn't use the standard SQL port. The solution was to prefix the data source/server in the connection string with Data Source=tcp:xxx.xxx.xx.xxx to always ensure it connects via TCP
The problem was that SQL was configured to allow both TCP and Named Pipes. Sometimes it would try and connect with the latter which doesn't use the standard SQL port. The solution was to prefix the data source/server in the connection string with Data Source=tcp:xxx.xxx.xx.xxx to always ensure it connects via TCP
I'm currently working on an API, to access data from a SQL Server that is hosted locally. My app is being hosted through an Azure web app. I'm also using Entity Framework 6 in my application to access data. Since my data can't be in the cloud, I created an Azure Hybrid connection to create a relay to my SQL Server.
However, I keep running into this error (see below). I don't understand why this happens. I have checked my firewall rules to make sure that connections from Azure are being permitted. I have also verified that my connection string is correct and that I'm using the right port number. I also verified that remote connections are allowed on the SQL Server.
In case anybody is wondering I'm running SQL Server 2012. Does anyone have a fix for this issue? I would really appreciate it.
Thanks in advance.
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.
I'm very frustrated. I have a website running on Visual Web Developer 2008 Express with my local database, everything works great. I also have the same web site running on a production server. Everything was working great but tonight I did a "reset" on production.
I deleted a couple of table, re-created them and inserted data. Everything was ok at this time.
I deleted ALL the files via the FTP.
I used the module called "Copy website" in visual studio and copy the site to the website via FTP.
When I log on my website, here is the error I got:
Server Error in '/' Application.
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)
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: 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)
Nothing has changed related to SQL connection, this is OLD code that I always used.
My website is completely paralysed because of this and I feel sick inside because I feel there is nothing I can do.
Can anyone help me please?
Your connection string was probably overriden when you copied your new website version on the server. Please check the connection string in web.config and see if it is valid.
If you are connecting from Windows Machine A to Windows Machine B (server with SQL Server installed) and are getting this error, you need to do the following:
On Machine B:
Turn on the Windows service called "SQL Server Browser" and start the service
In Windows Firewall:
enable incoming port UDP 1434 (in case SQL Server Management Studio on machine A is connecting or a program on machine A is connecting)
enable incoming port TCP 1433 (in case there is a telnet connection)
In SQL Server Configuration Manager:
enable TCP/IP protocol for port 1433
I've resolved the issue. It was due to the SQL browser service.
Solution to such problem is one among below -
Check the spelling of the SQL Server instance name that is specified in the connection string.
Use the SQL Server Surface Area Configuration tool to enable SQL Server to accept remote connections over the TCP or named pipes protocols. For more information about the SQL Server Surface Area Configuration Tool, see Surface Area Configuration for Services and Connections.
Make sure that you have configured the firewall on the server instance of SQL Server to open ports for SQL Server and the SQL Server Browser port (UDP 1434).
Make sure that the SQL Server Browser service is started on the server.
link - http://www.microsoft.com/products/ee/transform.aspx?ProdName=Microsoft+SQL+Server&EvtSrc=MSSQLServer&EvtID=-1
check forthe followings :
Make sure your database engine is configured to accept remote connections
• Start > All Programs > SQL Server 2005 > Configuration Tools > SQL Server Surface Area Configuration
• Click on Surface Area Configuration for Services and Connections
• Select the instance that is having a problem > Database Engine > Remote Connections
• Enable local and remote connections
• Restart instance
Check the SQL Server service account
• If you are not using a domain account as a service account (for example if you are using NETWORK SERVICE), you may want to switch this first before proceeding
If you are using a named SQL Server instance, make sure you are using that instance name in your connection strings in your ASweb P.NET application
• Usually the format needed to specify the database server is machinename\instancename
• Check your connection string as well
the cause is that SQL SERVER is stopped from services.msc
a solution for this problem could be starting SQL SERVER from services.msc
I recently had this problem and it ended up being a port issue. My production SQL Server was set up at to be port 1427 instead 1433.
Just change the connection string to be
...data source=MySQLServerName,1427;initial catalog=MyDBName...
Hope this helps anyone who might be seeing this same issue.
I had the same problem with SQL Server 2008 R2 and when I checked "SQL Server Configuration Manager" My SQL Server instance had Stopped. Right Clicking and Starting the Instance solved the issue.
we have to enable TCP/IP property in sql server configuration manager
If your server was working and suddenly started erroring out, your server/instance stopped and connection settings were changed somehow.
For SQL Server 2008 here is how you can fit this:
Goto Start > All Programs > SQL Server 2008 > Configuration Tools > SQL Server Configuration Manager > SQL Server Services.
And here you'll see all the instances and their state.
The state of the instance you were trying to connect can be stopped here.
Double click on the instance and then click on connect.
It will connect and now go back and run your application, you will be able to connect with no error.
This solution assumes the error is not being caused by something wrong in your connection string.
In my case it was a very silly error. I was using a library to read the connection string out of a config file, and I forgot to double back slash.
For example I had:
localhost\sqlexpress which was read as localhostsqlexpress
when I should rather have had
localhost\\sqlexpress note the \
I had same problem regarding that i.e A network-related or instance-specific error occurred while establishing a connection to SQL Server.
I was using SQL Server 2005 (.\sqlexpress)` and worked fine but suddenly services stopped and gave me error.
I solved it like this,
Start -> Search Box - > Sql Configuration Manager -> SQL Server 2005 Services >and just Change Your SQL Server (SQLEXPRESS) State to Running by right clicking that service Sate.
I solved this issue by running the following command in an elevated command prompt as specified in this post.
net start mssqlserver
I had the same problem but found that it was because the password for my Service Account for the Database Engine had expired. The solution was to login to that account, fix this, then set the account so password never expires.
My remote sql server was expecting connection at a different port and not on the default 1443.
The solution was to add a "," after your sql server IP and then add your port like so 129.0.0.1,2995 (Check the " , " after server IP)
Please find the image for reference below.
I had the same error, and it turned out .NET created a database on localhost which I wasn't aware of. When I tried to get the site live it didn't create the database, so the code was pointing to a database that was non existent.
Hopefully this might help some other people out trying to troubleshoot.
I was using Microsoft SQL with asp.net MVC , it was working fine but today morning it gave me 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) (.Net SqlClient Data Provider)
I tried to Enable TCP/IP. I also started SQL in configuration manager but still cannot login to SQL Server 2014 using cloud server. It was working fine. I don't know what has happened to it.
Thanks
There is a really good YouTube vid at the bottom of this web-page so you can rule out a few more things - failing that I would have the server rebooted.
SQL Authority
In MS SQL Server Management Studio, have you checked the Properties of the SQL Server to ensure that Allow remote connections to the server is ticked?
If so then I would have to agree that it an on the Cloud Server rather than an issue with the SQL database.
Are you able to reboot the Cloud Server?
MS SQL Studio 2014 doesn't work very well with SQL 2005 or older if you running an old database version
You may want to ensure that the cloud server is allowing connections from your remote IP. It could be that your remote IP address has changed and you are no longer allowed access.
How to open the SQL database firewall for Microsoft Azure:
https://azure.microsoft.com/en-us/documentation/articles/sql-database-configure-firewall-settings/
i made an app on c# which has database connection and application works fine on my developement pc!
Application starts fine and everything else works fine which has nothing to do with DB but it throw an error when i try to execute query ?
I have Dotnetfx 2.0 installed on target machine what do i need to? Sql server?
Error is:
An error has occured 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. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified
p.s. its my first db application =S
SQL Server is a completely separate application from the application you wrote and are distributing. If your application does not connect to an existing SQL Server running somewhere on the network you will have to install and configure SQL Server as part of your application's installation.
In addition you will either need to install / create a database as part of your application's installation, or else your application needs to be able to detect the absence of the database and build it itself on first startup.
As Marek said, the connection string is the most likely culprit, and I believe on SQL 2008 you have to explicitly allow TCP connections via:
SQL Server Configuration manager
Select SQL Server Network
Configuration Select Protocols for your instance
Right click on TCP/IP and "Enable"
Make sure your connection string looks something like this:
"Server=(local)\\SQLEXPRESS;Database=Your_DB_Name_Here;uid=sa;pwd=password;"