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Editorial Team
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Asked: 2026-05-27T03:06:33+00:00

I am not sure what’s going on exactly as I can’t establish a strict

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I am not sure what’s going on exactly as I can’t establish a strict linear correlation between
events. But below you’ll find my connection string, at times it works, other times when I open the app/project I am building (no changes made) it doesn’t and gives me various errors and reasons.

<add name="EFDbContext"
     connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Program Files\Microsoft SQL Server\MSSQL10.SQLEXPRESS\MSSQL\DATA\EFDbContext.mdf;MultipleActiveResultSets=true;Integrated Security=True;User Instance=True"
     providerName="System.Data.SqlClient" />

Errors include:

Unable to complete operation. The supplied SqlConnection does not specify an initial catalog.

or

saying Amin-PC\Admin has no access rights (I am logged in admin)

Also when I try to add a new connection at times it will tell me I have no access rights or database already exists or just adds it normally!

I tried explicitly starting visual studio as administrator and this seemed to help with the denied access to the db issue.

Basically I don’t know what the heck’s going on.

Have recently started with .net and it has been easy coding for asp.net mvc framework until I got to interacting with underlying asp.net infrastructure, connection strings, outdated (noon-entity framework ready) membership provider etc.

And now don’t know what’s going on with the SQL Server Express edition that gets installed a long with VS2010.

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1 Answer

  1. Editorial Team

    My recommendation would be: since you already have a server instance (.\SQLEXPRESS) installed – attach your databases to the SQL Server Express instance, and then use them under their database name (instead of using the shaky AttachDbFileName= method).

    So:

    • launch your SQL Server Management Studio Express
    • find your MDF files you want
    • use Server > Attach Database to attach the MDF/LDF to the server – give it meaningful name
    • from that point on – use the database on the server and don’t attach MDF’s on the fly….

    Your connection string would then look something like:

    server=.\SQLEXPRESS;Database=YourEFDatabaseName;Integrated Security=True

    I find this method is typically much more reliable and predictable – the AttachdbFileName= and User Instance=true are supposed to be easier, but tend to be more confusing that anything else….

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