An attempt to attach an auto-named database for file …database1.mdf failed

I am getting the following error while debugging my visual studio 2010 website:

An attempt to attach an auto-named database for file C:\Users...\Desktop\Dpp2012New\App_Data\dppdatabase.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share.

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: An attempt to attach an auto-named database for file C:\Users...\Desktop\Dpp2012New\App_Data\dppdatabase.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share.

Here is my connection string from my web.config:

<connectionStrings>
    <add name="ApplicationServices" 
         connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\aspnetdb.mdf;User Instance=true" 
         providerName="System.Data.SqlClient"/>
    <add name="ConnectionString" 
         connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\dppdatabase.mdf;Integrated Security=SSPI" 
         providerName="System.Data.SqlClient"/>
</connectionStrings>

And I access it from my website as:

Dim connectionString As String = ConfigurationManager.ConnectionStrings("ConnectionString").ConnectionString

The stacktrace shows the error line as:

 Dim conn As New SqlConnection(connectionString)
 Dim dr As SqlDataReader
 conn.Open() 'This is the error line as per stacktrace

I have given the needed permissions to the above folder so it can not be the " or specified file cannot be opened" issue. If we look at all the posts related to the same error in this forum, clearly the profoundness of this error can be found out. However, none of the solutions solves my issue. Some of the resources which I have tried are:

I eagerly await a solution.

ray abu

I had this problem also and it was a pain. I configured my connection string and managed to solve the problem. In the connection string I replaced the value |DataDirectory|\dbfilename.mdf for AttachDbFilename property, with the path to the file. |DataDirectory| can only be used if the database file is in the App_Data folder inside same project.

So changing the AttachDbFilename property to the direct path of the mdf file, fixed my issue.

AttachDbFilename=C:\MyApp\App\DAL\db.mdf

I hope this works for you.

user3198801

Try to create your connection string as below:

 <add name="ECommerce" connectionString="Data Source=(localdb)\v11.0;Initial Catalog=C:\USERS\dL\DESKTOP\DATABASE\MYSHOP.MDF;Integrated Security=True;Connect Timeout=15;Encrypt=False;TrustServerCertificate=False" providerName="System.Data.SqlClient"/>

It's working for me.

I had a similar error, but using a connection configured in code, rather than a config file. The solution for me was simply to add the "Initial Catalog=MyDatabase" part. My code now looks like...

DbConnection connection = new SqlConnection(String.Format(@"Data Source=.\SQLEXPRESS; Integrated Security=SSPI; AttachDbFilename={0}; User Instance=True; Initial Catalog=IPDatabase;", Location));

Location is a full path to an mdb file, that does not have to exist yet.

<add name="Connections" connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;User Instance=True" providerName="System.Data.SqlClient"/>

One of the most annoying errors when developing web apps in .Net. I had this issue on a project I was doing a year ago. This is what worked for me: I've logged in with sa account to SQL Management Studio and attached the database to the object explorer (Databases -> Right Click -> Attach). Then I've opened Security->Logins->[myWindowsUsername] and edited User Mappings tab, giving dbowner rights to the attached database.

I'm sure you can do those things without Management Studio, with console commands, but I'm not that good with T-SQL and can't give you advice on that.

check your web-config file, there may be more than one connection string having same name

Mine was an EF code-first project and it comes up when the file has been deleted. Running Update-Database from the Package Manager Console makes the DB and its fine.

Error was fixed for me after I changed this

ConfigurationManager.ConnectionStrings[0].ConnectionString

to this

ConfigurationManager.ConnectionStrings["myconnection"].ConnectionString

I have changed the installation folder from program files to C directory while I am installing the app. then my problem is solved

well I think reason is that in your database directory, contains a .mdf file which has the same name. So best thing is to give the full path you can just replace the AttachDbFilename. just simply get the fullpath of the database file and assign it into the AttachDbFilename which is in app.config file.

In most cases, the unit test project is separated from the main project. This causes the generated connection string to be invalid as it fails to find an app_data folder, if your db is local to the solution.

You can just replace the |DataDirectory| with a relative path to your db in your main project if you need to connect to it from your unit test project.

Please check the path for your database on the connection string. I have the same error message and I later found out that the problem is a misspelled path.

I've been trying mdf portability in my application, so I've been using

    public DbContext IoDatabase()
    {
        var directory = System.IO.Directory.GetCurrentDirectory();
        var connectionString = @"Data Source=(localdb)\mssqllocaldb;AttachDbFilename=" + directory + "\\App_Data\\ITIS.mdf;Integrated Security=True;Connect Timeout=30;";
       return  new NerdDinners(connectionString);
    }

with nerdDinners, I can't remember where I found it, being

public class NerdDinners : DbContext
{
    public NerdDinners(string connString)
    {
        Database.Connection.ConnectionString = connString;
    }
}

Then I can use the return type as a DbContext.

The main thing I ran into was that GetCurrentDirectory() gets the compiled file path, not the project file path, so deployment should be set to GetCurrentDirectory and the mdf should be copied on compile, not reference the actual App_Data. Include your mdf in your project and go properties on it. Set the copy to output directory.

Istvan Heckl

I had the same problem with EF. The absolute path solution worked. But it is not a nice solution if you want to move your program to a new location. For me this was the problem.

VS searches the mdf file in the debug folder
There is an .mdf file in the project folder, sometime VS sync the two files
For some reason the .mdf file was not synced into Debug

My workaround:

Copy the .mdf and .ldf file to a temp folder
Make a connection for it in vs/server explorer
When you add the ADO.NET use the new connection
VS offers to copy the .mdf file into the project folder, accept it
Now the .mdf file will appear in the debug folder as well
Delete the connection for the temp folder, create a new one to the project folder

what I've found so far to solve the problem, if you create mdf file in the below way, it would work just fine for visual studio.

Right-click on the data connection in the server Explorar->add connection->Select Microsoft SQL Server Database File and choose database name and select okay. Then this prob doesn't arise. Follow the video: youtube link

Looks like there are lots of causes for this...Here was mine.

The clue was on the last line of the error message...

System.Data.SqlClient.SqlException: 'An attempt to attach an auto-named database for file Q:\Folder\FileName.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share.'

...or it is located on UNC share.

In trying to replicate a production environment... I originally had physical drive Q:. After my dev machine tanked..I rebuilt and just created a mapped drive. Started getting this error...and then went back and just created another Q: partition and the problem was solved.

I had a similar problem after i moved my db to a folder within the same project.

All i had to do finally was to to properties of the database, copy the path listed under 'identity' and replaced the path at 'AttachDbFilename='.

Worked just fine.

Natalia J.

I had the same problem,and i think i figured it out.in the connection string make sure that the connection string looks like this:

<connectionStrings>
  <add name="ApplicationServices"
    connectionString="data source=.\SQLEXPRESS;
                      Integrated Security=SSPI;
                      AttachDBFilename=|DataDirectory|\aspnetdb.mdf;
                      User Instance=true"
    providerName="System.Data.SqlClient" />
  <add 
    name="NorthwindConnectionString1" 
    connectionString="Data Source=localhost;
                      Initial Catalog=Northwind;
                      Integrated Security=True" 
    providerName="System.Data.SqlClient" />
</connectionStrings>

Now, the first

<add 
  name="ApplicationServices" 
  connectionString="data source=.\SQLEXPRESS;
                    Integrated Security=SSPI;
                    AttachDBFilename=|DataDirectory|\aspnetdb.mdf;
                    User Instance=true"
  providerName="System.Data.SqlClient" />

is what appears by default in the web.config. Leave it unchanged,and add another connectionstring

 <add
   name="NorthwindConnectionString1" 
   connectionString="Data Source=localhost;
                     Initial Catalog=Northwind;
                     Integrated Security=True"
   providerName="System.Data.SqlClient" />

with your parameters. This is working for me. Hope it helps.

来源：https://stackoverflow.com/questions/12566036/an-attempt-to-attach-an-auto-named-database-for-file-database1-mdf-failed

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