I'm facing some issues trying to connect to an SQL Server 2005 using Entity Framework.
I've this small WindowsForm application using a System.Data.SqlClient.SqlConnection:
SqlConnection cnn = new SqlConnection("Data Source=servername\\sqlhotel;Database=mydatabase;User Id=myusername;Password=mypassword");
try
{
cnn.Open();
MessageBox.Show ("Connection is Open ");
cnn.Close();
}
catch (Exception ex)
{
MessageBox.Show("Can not open connection ! ");
}
This is working fine on my server (I'm getting the "Connection is Open" message), but in my ASP.NET Web API application using Entity Framework 6 I'm getting this error using the above connection string:
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)
Why?
Ensure that TCP/IP is enabled in SQL Server Configuration Manager, and that SQL Server is allowed through your Windows Firewall (on the server) if you are trying to connect remotely. You can add it to the white list if not, but for security reasons this is probably a bad idea - and definitely a bad idea if it is a production server.
Related
I build a simple CRUD app in C# and used server based database file (.mdf) in my Project. My connection string is like this:
public string connectionString { get; set; } = $"Data Source=(LocalDB)\\MSSQLLocalDB;AttachDbFilename=\"{AppDomain.CurrentDomain.BaseDirectory}Passwords.mdf\";Integrated Security=True";
In my computer application works fine just I want, but after send to my friend, he got error that can't connect or find SQL database. Error text 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: SQL
Network Interfaces, error: 26 - Error Locating Server/Instance
Specified
So we download SQL server express 2019 for him (I use 2017 by the way) and after that, still he get the same error. I dont understand what is the problem. Any succession?
I cannot connect to a particular SQL Server 2008 database server from C#.
I am able to connect using SSMS, and run queries using SQLCMD, but when I try to connect from C# using the SqlConnection it fails to open the connection with a 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)
Here is my code:
using (SqlConnection conn = new SqlConnection(#"Server=LDNPSM050000137\PLN000000014T;Initial Catalog=MiscData;Integrated Security=True;"))
{
//exception occurs on this line
conn.Open();
//use connection
conn.Close();
}
I get a similar response using ODBC:
string connectionString = #"Driver={SQL Server Native Client 10.0};Server=LDNPSM050000137\PLN000000014T;Database=MiscData;Trusted_Connection=yes;";
using (OdbcConnection connection = new OdbcConnection(connectionString))
{
connection.Open();
}
This fails with an OdbcExcpetion:
ERROR [08001] [Microsoft][SQL Server Native Client 10.0]SQL Server Network Interfaces: Error Locating Server/Instance Specified [xFFFFFFFF].
ERROR [HYT00] [Microsoft][SQL Server Native Client 10.0]Login timeout expired
ERROR [08001] [Microsoft][SQL Server Native Client 10.0]A network-related or instance-specific error has occurred while establishing a connection to SQL Server. Server is not found or not accessible. Check if instance name is correct and if SQL Server is configured to allow remote connections. For more information see SQL Server Books Online.
I have checked the server and instance name are correct, and the server is configured to allow remote connections because I can connect through SSMS. Does anybody have a suggestion of what the problem could be or how to resolve this?
Update:
In case this helps somebody diagnose the problem - This is specific to my machine/user account. My colleague can run the code fine from his machine. I am also able to connect to my local instance using a connectionstring with the appropriate changes to the Server and Initial Catalog.
The error occurs for all remote database servers.
I'm not sure if this is specific to my company's specific IT infrastructure - but the reason this was not working for me was because the project was saved in My Documents which stored on a network share. Apparently .NET will not let you connect to a remote database server when the executing code is located on a network share - it work fine when I copied the project to my local drive. I am using Windows 7 and Visual Studio 2012.
Network shares by default have partial trust, so things that work when a project is on your local drive, e.g. connecting to remote server, won't from network location.
You can give the network location full trust (https://msdn.microsoft.com/en-us/library/zdc263t0(VS.80).aspx) or move your project onto your local drive.
I think the problem is the Server value in your Connect string:
From MSDN
I think you need to do this:
Server=tcp:LDNPSM050000137\PLN000000014T
Server=np:LDNPSM050000137\PLN000000014T
Depending upon whether you want to use TCP or Named Pipes...
I am trying to make a registration page, that stores Username, password,and email,
but
When ever i try to Connect database using this string,
SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["RConnectionString"].ConnectionString);
conn.Open();
Following Error appears:
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)
I searched everywhere, but it didn't helped me..
The issue starts from web.config and the connection string that is located at RConnectionString according to the code line you give.
Locate this string and fix it to been able to connect to your database.
And some examples here: Setting up connection string in ASP.NET to SQL SERVER
myConnection = new SqlConnection("user id=champion3_test;" +
"password=test;server=10.168.1.58;" +
"Trusted_Connection=true;" +
"database=champion3_sabdb; " +
"connection timeout=30");
This code gives the error:
Thrown: "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)" (System.Data.SqlClient.SqlException) Exception Message = "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)", Exception Type = "System.Data.SqlClient.SqlException", Exception WinRT Data = ""
Here are some screenshots that might help with debugging of my server's settings:
http://imgur.com/a/PeRby
I know that 'champion3_test' is a valid user id
'test' is a valid password for champion3_test
the database name is 'champion3_sabdb'
SQL server isn't MySQL. If you are using MySQL, download the MySQL .NET Connector and use their connection class, MySqlConnection.
To learn how to use the MySQL Connector, you can start here.
You can download the MySql Connector for .Net here.
Once you've installed the driver, you can connect using the MySql Connector classes:
string connStr = "server=localhost;user=root;database=world;port=3306;password=******;";
MySqlConnection conn = new MySqlConnection(connStr);
I'm trying to connect to a database but nothing I try works.
SqlConnection conn = new SqlConnection(#"Data Source=C:\Users\Gerard Foley\Desktop\Northwind.sdf");
conn.Open();
No matter what I try I just get the 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: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)
I stole the connection string from Database Explorer -> Properties -> Connection String. What am I missing? I can get the tables to show up in a DataGridView fine (by dragging from Data Sources), but I want to use my own UI and queries. I just can't seem to figure this ADO thing out.
Using c# express 2010 and sql server express 2008.
for the proper connection string to use to connect to SQL Server have a look at:
http://connectionstrings.com
the connection string you are using now is strange, it should contain server name and database name, see link above for examples...
GOT IT. I should have been using Sql*Ce*Connection. The connection string was fine.
You need to specify 'AttachDbFileName' in the connection string. See the examples for sql server express here: http://www.connectionstrings.com/sql-server-2008.