Can't connect to named instance of sql server asp.net c#

Question

I can't connect via ASP.NET to a named instance of a sql server, that itsn't the default instance. My servername is NAMEOFSERVER\NAMEOFINSTANCE.

If I try to connect to the default instance of the server, it works.

I use the following connection string:

connection_string = "Data Source=" + servername + ";Initial Catalog=" + db_catalog + ";User Id=" + user + ";Password=" + password + ";persist security info=False;Trusted_Connection=No;Connection Timeout=1000"

The SQL Server Browser service is running.

Yes, connecting via sql management studio is working perfectly fine. — moons
– moons, Commented Dec 12, 2017 at 12:33
This is not a connection string, this is string concatenation. Debug your code and inspect that connection_string contains what you expect it to. You may have a \n escape sequence in there, for example. — CodeCaster
– CodeCaster, Commented Dec 12, 2017 at 12:34
I logged connection_string, and it contains what I expected it to. The strange thing is: my other named instance on the same server has got the same connection string (only the name of the instance inside the servername differs) and there the connection works — moons
– moons, Commented Dec 12, 2017 at 13:49

rodrigogq · Accepted Answer · 2017-12-12 13:38:30Z

-1

Make sure your connection string have the pattern above:

var connectionString = $"Data Source=myServerName\\myInstanceName;Database=myDataBase;User Id=myUsername; Password=myPassword;",

Also, make sure you can connect via SQL Management Studio, since instances of the SQL Server can limit access to some users (make sure you connect to the same user name + password you want your app to use).

EDIT

If the user you are using to connect is not part of a Windows account, please open your instances security configuration and make sure Mixed Mode is enabled.

edited Dec 12, 2017 at 13:38

answered Dec 12, 2017 at 12:31

rodrigogq

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2 Comments

CodeCaster Over a year ago

Server and Data Source are the same thing.

rodrigogq Over a year ago

@CodeCaster Thanks, I updated my answer. My point was to make sure that the pattern was correct, including the slashes. I also updated with some other tips.

Steef · Accepted Answer · 2017-12-12 12:43:34Z

-3

You might want to check if your variable "servername" contains a double backslash. This is needed because backslash is a escape character.

connection_string = "Data Source=" + servername.Replace("\\", "\\\\") + ";Initial Catalog=" + db_catalog + ";User Id=" + user + ";Password=" + password + ";persist security info=False;Trusted_Connection=No;Connection Timeout=1000"

answered Dec 12, 2017 at 12:43

Steef

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3 Comments

moons Over a year ago

My variable contains one backslash: "nameofmyserver\nameofmyinstance" - is this a problem?

Steef Over a year ago

Did you try the ConnectionString I added? There the backslash is converted to a double backslash. My suggestion is that it will work when you try it like that.

CodeCaster Over a year ago

You need to escape a backslash when specifying strings in source. You don't need a double backslash in the actual string.

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