I have created software in c#.net which has some database into it. After creating a .exe file it works fine in my system but after installing that
application in another system it gives following error.
Error: A network-related or instant 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 connection. (provider: SQL Network Interfaces, error: 26 - Error locating server/instance specified).
I have tried installing SQL Server and .net framework in client's machine but still, it's not working.
Do I need to install anything else on the client's pc to run my application?
Check the connection string to the database. The connection string should point to the SQL database the Client has access to. Most of the time this is not the same as the one you are using while developing.
Change connection string of localhost to IP address of Database PC.
You are going to have to add a connectionstring to your App.config file.
<connectionStrings>
<add name="ConnectionString" connectionString="Data Source=PRANOYPC\SQLEXPRESS; Initial Catalog=DatabaseName; Integrated Security=True;" providerName="System.Data.SqlClient"
</connectionStrings>
If you are using Windows authentication you can leave Integrated Security = True if not you will have to provide the authentication for the Database.
Also you have to make sure that the Client has access to the database that you are trying to access.
I have a separate dll that handles connections to the database and thus holds the models and the api context. the app.config 'acts' like the web.config and holds the connection details However I keep getting the following 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)
So I copied the connection string from another more traditional mvc web.config file and the error still occurs.
Oddly, the following works:
update-database -verbose
My app.config has the following connection string:
<add name="DefaultConnection"
connectionString="data source=(LocalDb)\v11.0;initial catalog=APIEntities-01;persist security info=True; Integrated Security=SSPI;MultipleActiveResultSets=True"
providerName="System.Data.SqlClient" />
and the dbContext points to it
public ApiContext() : base("DefaultConnection")
{
}
As I say, this works in a traditional MVC web.config, but using a dll that references Entity Framework and such like it seems to not be able to locate the database. Any suggestions?
EF 6
I suppose that the connection string because the "data source=(LocalDb)\v11.0;initial catalog=APIEntities-01" is a path local to your PC. You must provide the real SQL Server that you need to use. See this:
Change default location of LocalDb
Some times its hapen when sql server failed to open. Then open sql server configuration and then select (sql server Services) see on state which are stopped or manual...right click on then and make start...then the problem will be solved.
I am working on Desktop application in WPF and creating SqlRepository with LocalDB to store data. I am using following tools
Visual Studio 2013 Community with update 2
Entity Framework 6.1.2 for Code first migration
I have created local database with Microsoft SQL Server Database File (SqlClient) configuration. Database created successfully and below is connection string fetched from Sql
Data Source=(LocalDB)\v11.0;Initial Catalog=D:\USERS\USERNAME\DOCUMENTS\TestDatabase\testdb.MDF;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False
I am using same connection string in app.config. I can view database object in SQL Server Database explorer in Visual Studio. But when run update-database command in Nuget package manager console, I am getting below 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 had similar problem and fixed it when I changed the "start-up project" from another module to the module containing references to all other projects in the solution.
Right-click module >> click "Set as StartUp Project"
Diego's answer is correct.
This problem occurs when there is no connection string in project marked as startup project. Then EF tries to connect to some default database engine to perform update. In my case it tried to use express, and for some reason it couldn't connect. And the error was thrown.
Run your "update-database" with option "-Verbose". One of the lines there shows which StartUp project is used. Check your connection string in this project, or change the startup project to the one that has correct connection string. That solves the problem.
As explained in other answers, the problem usually comes from having the wrong Initial project in Package Manager Console.
In my case the console was ignoring the value I selected in the Default Project drop down list, and also the -StartUpProjectName parameter, and reproducing the wrong behavior of trying to connect to some default database engine, as Mikk's answer describes, in my case using a SqlExpress engine.
My problem was caused by a wrong solution configuration: if your solution has several projects and is meant to be run with the configuration option "Multiple startup projects", but you just downloaded it from your source code control repository, then it is possible that the default configuration option "Single startup project" is being applied to the solution (this config value usually is not checked-in in the source code control). In this case the Package Manager Console just ignores the startup project selected in its combo and just applies the default startup project in the solution, which may not have a connection string, as specified in Mikk's answer.
So I fixed it by changing the solution properties: Common properties / Startup project / Select Multiple startup projects instead of Single startup project, and after that the Package Manager Console would accept the Project name and update the right database.
I was able to solve this by adding parameters to the update-database command:
update-database -StartupProjectName MyApp.Web -ConnectionStringName MyAppConnectStringInWebConfig
I solved this error changing the initial project to the Entity Project.
Look:
Update-Database -Verbose
Using StartUp project 'SCVE.Web'. <-- this ir error
Using NuGet project 'SCVE.EntityFramework'.
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)
This error message informs you that it is not possible to connect to SQL Server. The possible reasons and their elimination is described below:
1) SQL Server is not started. Starting of it will allow you to see your SQL Server/instance in the drop-down list of available SQL Servers.
Go to the Start menu -> Control Panel -> Administration Tools ->
Services.
In the list of services find SQL Server (instance name, by
default it is EZPARTS5) and check its status, it must be Started
(if it is not started, then right click on SQL Server and select
Start from the context menu).
2) Firewall is blocking port 1433 (MSSQL standard port for connections). It can be disabled following the steps below:
Go to the Start menu -> Control Panel -> Administration Tools ->
Services.
Find Firewall service, it must be disabled (if it is not, then right
click the service and select Stop from the context menu).
Note: More information on this can be found on the official Microsoft site: Link
3) TCP/IP protocol is disabled for MSSQL protocols. To enable it, see the steps below:
Navigate to SQL Server Configuration Manager in the Start menu.
Specify settings for TCP/IP protocol in SQL Server Configuration
Manager.
Restart the computer.
Note: More information on this can be found on the official Microsoft site: Link
4) Make sure your database engine is configured to accept remote connections (If you are using centralized database):
Open SQL Server Management Studio.
Right click SQL Server instance -> Properties -> Connections ->
Check the Allow remote connections to this server box.
Go to the General section and check name of SQL Server specified in
the Name field.
5) If you are using a named SQL Server instance, make sure you are using that instance name in your connection strings. Usually the format needed to specify the database server is machinename\instancename.
6) Make sure your login account has access permission on the database you used during login.
Alternative:
If you still can’t get any connection, you may want to create a SQL account on the server, a corresponding SQL user on the database in question, and just use this username/password login data to connect to SQL Server.
Referred from this link
Try with this Connectionstring:
<connectionStrings>
<add name="DefaultConnection" connectionString="Data Source=(LocalDb)\v11.0;AttachDbFilename=D:\USERS\USERNAME\DOCUMENTS\TestDatabase\testdb.MDF;Initial Catalog=testdb;Integrated Security=True" providerName="System.Data.SqlClient" />
</connectionStrings>
If you are trying to connect to Sql Server instead of localdb then make sure the default connection factory in web.config file is as below:
<defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework">
<parameters>
<parameter value="Data Source=.\SQLEXPRESS2012; Integrated Security=True; MultipleActiveResultSets=True" />
</parameters>
</defaultConnectionFactory>
I had this same problem with a freshly created ASP.NET project.
First I tried to set the startup project as mentioned above. There was no startup project selected and I was unable to select one.
Ultimately I updated my Visual Studio from 2015 Update 1 to 2015 Update 3 and
update-database
executed without problems.
PM>Update-Database
error and solution which I did today in 4 hours.
I am very much new in .net coding, but yes in PHP I have 10+ years experience.
It took me 4 hours to solve this.
1.My first Mistake: I was not having Microsoft SQL Server 2019 in my laptop locally I was having this through AZURE which is not works for localhost, so I installed this locally after download, it took around 2 Hours.
2.Second changed mistake=
"DevConnection": "Server=localhost;Database=PaymentDetailDB;Trusted_Connection=True;MultipleActiveResultSets=True;"
then it works for me
A friend of mine setup a Jenkins build server with automatic deployment to Azure. The website used to work fine after deployment, but after we branched our solution and then merged it again (after changing from .aspx to razor) the website displays the following error (locally everything works fine):
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)
Unfortunately we (the two that are left behind) cannot ask our friend how to solve this since he is on a vacation.
After searching on the internet we think it has something to do with our connection string that might be changed. Locally we can connect to the remote Azure database via the "Connect to Database" option in the Visual Studio Server Explorer. When we right click this connection and copy the connection string into our web.config and/or publish profile we still get the same error message on the website.
Our connection string in the web.config looks like this:
<add name="DefaultConnection" connectionString="Data
Source=*******.database.windows.net;Initial Catalog=blablaAszH;Persist
Security Info=True;User ID=testserver#blabla;Password=ourpassword"
providerName="System.Data.SqlClient" />
I do not know what other relevant information I can post but if you ask for it I will place it here.
(The main goal is actually just to deploy the website. But we cannot do this via Visual Studio since only our friend knows the username and password and he's disconnected from the world. These are not the same as in the connection string since when we publish from Visual Studio it says the web deployment task failed because of a wrong username and password. So we need to publish via committing our project to SVN and Jenkins doing the deployment.)
Does anyone here know how to solve this issue or with what it might be related?
I have two MDF files in a directory down the AppData/Local path. If I attempt to open them using LocalDb.
My connection string is of the form:
Data
Source=(localdb)\v11.0;AttachDbFilename="C:\Users\Anna\AppData\Local\CaseTrakker
Software\CTDynamoDisconnected\CTDynamoDisconnected_Data.mdf";Integrated
Security=True;Connect Timeout=10
I have a sample desktop application that attempts to connect to this MDF, and I get this exception:
System.Data.SqlClient.SqlException (0x80131904): Cannot open database
"C:\USERS\ANNA\APPDATA\LOCAL\CASETRAKKER
SOFTWARE\CTDYNAMODISCONNECTED\CTDYNAMODISCONNECTED_DATA.MDF" requested
by the login. The login failed. Login failed for user 'IMA\Anna'.
If I move this file to any other location, or rename it (even to a name that is longer), I am able to connect to it.
There appears to be something peculiar about this location or something.
One other odd thing: it worked last week. So far as I am aware, nothing has changed on my machine or my Domain Security.
I'm at a complete loss as to what else to even try. Ideas?
Can you check if there is anything interesting in the LocalDB instance log file? It is located by default in %localappdata%\Microsoft\Microsoft SQL Server Local DB\Instances\v11.0 folder.
One cause of this problem is if you go into your C:\Users\[username] folder and delete the MDF and LDF files. If you do this, then that's akin to doing the same thing to full-blown SQL Server. The server instance still thinks it has the databases but they're obviously not going to work.
A work-around to the problem is to change the database name in your connection string and it should just work.
To actually fix the problem, open up SQL Management Studio, connect to server (LocalDb)\v11.0 (likely with Windows Authentication) and you can detach these databases this way.
In my case I had that DB for a while and mistakenly deleted its MDF and LDF files.
To solve this, I opened SQL Management Studio and connected to (localdb)\MSSQLLocalDB using Windows Authentication then created manually a new empty DB with desired name like that in web.config connection string
<add name="DefaultConnection" connectionString="Data Source=(LocalDb)\MSSQLLocalDB;Initial Catalog=myDb;Integrated Security=True;" providerName="System.Data.SqlClient" />