'instance failure' error while connection string is correct

Question

I have following code on page load event:

 Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        con = New SqlConnection("Data Source=14GRAFICALI\\SQLEXPRESS;Initial Catalog=sagar;Integrated Security=True")
        '-----------------------fill name ddl------------------------------'

        Try

            da = New SqlDataAdapter("select EmpName from empMaster_VB", con)
            ds = New DataSet()
            da.Fill(ds)
            For i As Integer = 0 To ds.Tables(0).Rows.Count

                ddlName.Items.Add(ds.Tables(0).Rows(i)(0).ToString())

            Next


        Catch ex As Exception

        End Try

        '--------------------------------------------------------------------'


        '----------------fill expence-------------------------------------'

        Try

            da = New SqlDataAdapter("select ExpName from expenceType_VB", con)
            ds = New DataSet()
            da.Fill(ds)
            For i As Integer = 0 To ds.Tables(0).Rows.Count

                ddlExpence.Items.Add(ds.Tables(0).Rows(i)(0).ToString())

            Next


        Catch ex As Exception

        End Try


        '---------------------------------------------------------------'



    End Sub

This code is to fill drop downs with names and expence values in database tables.

I am getting 'instance failure' error while executing the code.

I checked one of the answers on stack and checked my connection string. But, my connection string is also correct.

Please help me if anything else is missing in this code.

Are you opening the connection? – Milen Jul 15 '13 at 09:17 — Milen, Jul 15 '13 at 09:17
no, i am not opening the connection – C Sharper Jul 15 '13 at 09:18 — C Sharper, Jul 15 '13 at 09:18
add `con.Open()` before you do the Select statement – Milen Jul 15 '13 at 09:20 — Milen, Jul 15 '13 at 09:20
i removed // from datasource and made / and it worked. – C Sharper Jul 15 '13 at 09:31 — C Sharper, Jul 15 '13 at 09:31

score 70 · Accepted Answer · answered Jul 15 '13 at 09:14

70

As you got the error "instance failure", that might be the error with your SQL Server instance..

Make sure your SQL Server instance(MSSQLSERVER) is running, where you can check in: Services list. TO get into services list: open run dialog box and type: "services.msc" (without quotes) and hit Enter. That takes you to services management console, where you can check whether your instance in running or not..

If the problem still persists, then try using: Data Source=.\SQLEXPRESS instead.. :)

Happy Coding... :)

answered Jul 15 '13 at 09:14

Vidhya Sagar Reddy

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Try restarting your instance once.. :) – Vidhya Sagar Reddy Jul 15 '13 at 09:25
4

That could even work for .\SQLEXPRESS if the machine is local... :) – Vidhya Sagar Reddy Jul 15 '13 at 09:38
21

yup, // was issue. it worked on both, only i was not removing // and making it / . Thanks – C Sharper Jul 15 '13 at 09:51
4

Perfect solution. My connectionString previously was "Server=OWNER-PC\\SQLEXPRESS" and got Instance Failure after using EF6's update-database command. After changing it to "Data Source=.\SLQEXPRESS" all works great. – Jimmy Shaw Apr 08 '17 at 22:32

score 43 · Answer 2 · edited May 13 '23 at 18:18

43

I have the following connection:

Data Source=MyComputerName\SQL2012ENTERPRS;Initial Catalog=RESTFUL; User Id=myuser; Password=mypass123;

My server's identifier is: MyComputerName\SQL2012ENTERPRS

But since I'm use a string, I add another blackslash \ so the string becomes:

public string connectionString = "Data Source=DAFWKN409C67Q\\SQL2012ENTERPRS;Initial Catalog=RESTFUL; User Id=rest_user; Password=rest_pwd_01;";

I have forgotten that I must remove one of \ since I am not use the default string block, I use an XML file to save my connection string and then everything is okay so my suspicion is that your instance name is not correct.

This is my connection string it I use on a local pc using SQL Express:

string servername = @"Data Source=.\SQLExpress;Initial Catalog=Workshop;Integrated Security=True";

You should modify the above string with your server name and instance name and ensure it is correct.

edited May 13 '23 at 18:18

Skully

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answered Jul 24 '17 at 06:52

toha

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Was having issue with NLog and database target and this solved! – JMIII Jun 26 '18 at 19:46
1

I was having the same problem and this answer worked for me, I removed the double \\ in the data source name to a single \ – Gagan Jun 18 '19 at 20:27
I was also having the same issue and this solution worked for me. – sanjeewa Dec 28 '22 at 09:13

score 28 · Answer 3 · edited Jul 14 '18 at 20:42

28

I had this issue because I got the connection string from appsettings.Development.json:

"Server=msi\\DataBaseName;Database=Super25;Trusted_Connection=True;"

but when I changed to

"Data Source=msi\DataBaseName;Initial Catalog=Super25;Integrated Security=True;"

solved!

edited Jul 14 '18 at 20:42

Paul Roub

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answered Jul 14 '18 at 20:37

Almeida

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score 26 · Answer 4 · answered Nov 09 '18 at 08:46

26

in my case just kick up the double \\ to one slush \ :=)

answered Nov 09 '18 at 08:46

Hamit YILDIRIM

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I didn't update my exe configuration file and some how this got updated with two back slashes. I checked my source control and it was a single slash up until this started happening. You were right on the money; thanks. – Zonus Aug 26 '19 at 15:09
1

this worked for me, many time in c# code we pur @ then there is no need of \\ just use \ if @ is preceding the connection string. – Tushar Kshirsagar Oct 27 '19 at 17:26
Worked like a charm. Two slashes were fine in ASP.NET Core project, but crashed in plain ASP.NET. – Eternal21 Jul 24 '20 at 15:19

score 10 · Answer 5 · answered Nov 15 '19 at 18:51

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The root cause is Regular literal ("Backslash: \") and Verbatim literal ("@"Backslash: \"") . Reference https://csharpindepth.com/Articles/Strings

answered Nov 15 '19 at 18:51

L.Guan

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score 5 · Answer 6 · answered Jun 20 '16 at 17:03

5

Use the wildcard "@" before "Data Source" declaration. someting like this: connetionString = @"Data Source=...

So you'll be able to use only a back slash. Like this: @"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\jcabarros...

answered Jun 20 '16 at 17:03

JBarros

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score 2 · Answer 7 · answered Sep 17 '22 at 21:44

Your answer lies in the connected services. edit provider and select the three dots once you find your database select advanced in the advanced you will see your connection string which looks like below.

Data Source=Server\ServerInstance;Initial Catalog=yourDatabaseName;Integrated Security=True

You can add more services and configure more there.

score 1 · Answer 8 · answered Oct 11 '19 at 21:10

I know this is an old thread, but perhaps a good update. I couldn't find a good answer on the web search.

I got the same 'Instance Failed' error when trying to reference a DbContext from another project in the same solution. The 1st project had a DbContext and the connection string, and the 2nd project in the solution was trying to reference it. The 1st app ran ok on its own, issue only occurred when running the 2nd app.

The issue was that the app.config file that had the connection string from the 1st project was not in view/scope of the 2nd project. So the connection string wasn't assembled.

My solution was to copy the app.config from the first project to the second project.

This was on VS 2019.

Hope this helps

'instance failure' error while connection string is correct

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