C# Ado.net Entity Framework error?

Question

I create a project to display a list of student on Database (the current.net framework version is 4.6.1). The wizard ask me to add database to the project and I accept it.

When I build the project on Debug mode, everything works fine on Windows 10.

I copy the debug folder to windows 7 and try to run the project, it shows me the error message.

System.Data.EntityException: The underlying provider failed on Open.

I try to install the .net framework 4.6.1 for windows 7 but it didn't work. This is the list of installed programs on windows 7:

The list of installed programs on windows 10:

I really don't know why my project didn't work on windows 7, are there some missing files or frameworks?

Thanks for your reading :D

I think the project can run alone without SQL server. It just depends on .net framework? — Hoang Viet
– Hoang Viet, Commented Sep 19, 2017 at 1:10
Windows 7 seems not working with SQL Local Database 2014. I installed SQL 2012 Express Local Database and it worked! — Hoang Viet
– Hoang Viet, Commented Sep 21, 2017 at 4:21

YaniMan · Accepted Answer · 2017-09-18 17:27:24Z

1

"...LocalDB is a feature of SQL Server Express targeted to developers." You can use LocalDB on your development machine, but don't expect it to be working on other machine. I can't tell you an exact solution as it depends on what you are allowed to do. Moving to a "real" database maybe.

answered Sep 18, 2017 at 17:27

YaniMan

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5 Comments

Hoang Viet Over a year ago

I tried to use the original database by modifying the connection string in App.config (point to C:\TestDatabase.mdf). Then I copy all of them to same location in windows 7, but it still show the error.

YaniMan Over a year ago

I think, this is because LocalDB (SQL Express) isn't installed on the Win 7 machine. Could you please post the original and the modified connection string?

Hoang Viet Over a year ago

This is the created connection string when I attached database to my project: <connectionStrings> <add name="DemoDatabaseEntities" connectionString="metadata=res://*/Model1.csdl|res://*/Model1.ssdl|res://*/Model1.msl;provider=System.Data.SqlClient;provider connection string="data source=(LocalDB)\MSSQLLocalDB;attachdbfilename=|DataDirectory|\DemoDatabase.mdf;integrated security=True;connect timeout=30;MultipleActiveResultSets=True;App=EntityFramework"" providerName="System.Data.EntityClient"/> </connectionStrings>

Hoang Viet Over a year ago

That means the SQL Express is required on windows 7?

YaniMan Over a year ago

Sure. It contains LocalDB. Also would worth figuring out where |DataDirectory| points, but a simple google search did not yield and usable results for me and i'm on a run.

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