Entity Framework The underlying provider failed on Open

Entity Framework The underlying provider failed on Open

Below is my connection string:

connectionString="metadata=res:///EDMX.Test.csdl|res:///EDMX.Test.ssdl|res://*/EDMX.Test.msl;provider=System.Data.SqlClient;provider connection string="Data Source=home_computer;Initial Catalog=db_Test;Persist Security Info=True;User ID=testUser;Password=$1234;MultipleActiveResultSets=True""

Here is the code where the program stuck:

EDMX.TestingEntity context = new EDMX.TestingEntity();    var query = from t in context.User              where t.UserName == _userName              select t;  

After running the above code, I check the variable query and found an exception

The underlying provider failed on Open.

I've checked:

1. Connection between server and computer is normal
2. I can login to the database with username testuser and with password $1234
3. I have checked the security settings in database (SQL Server) that permission has been granted to testUser

Why does this exception happen? I'm using .net 4.5

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Added:

I tried again, look at the inner exception and it was: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)

I know it might be a network problem but I've turned off the firewall of server and also my computer and tried again but still not success..

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Just now Copied the connectionstring to a program to test this connection and it was functioning well..

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I just rollback all changes and test again and it worked

Answer by Vinay Singh for Entity Framework The underlying provider failed on Open

Please check the following things first.

While generating the Edmx you would have given a name to you connection string. that gets into the app config of the project with the Entity.

Have you copied the same connection string to your main Config file. Also the Name should be same as which you have given while generating the EDMX file.

Answer by Ramesh Sivaraman for Entity Framework The underlying provider failed on Open

Seems like a connection issue. You can use the Data link properties to find if the connection is fine. Do the following,

Create a blank notepad and rename it to "X.UDL" Double click open it, under connections tab choose the server name/enter the name use the correct credentials and DB OK to save it.

Now open the file in Notepad and check, compare the connection string properties with this..

Answer by Amar Pawar for Entity Framework The underlying provider failed on Open

Try this- Open the command prompt as administrator and type this netsh Winsock reset

Restart your system and try again.

Answer by user3290439 for Entity Framework The underlying provider failed on Open

My client reported this error. I found that he was messing with *.ldf files. He copied *ldf file on one database and renamed it to match a second database (which I asked him to place in a folder).

I replicated the same scenario, and got this same error in my development system. Error got fixed after deleting the *ldf file(s).

Answer by Oamsalem for Entity Framework The underlying provider failed on Open

If you are using a local .mdf file, probably a sync software such Dropbox attempted to sync two log files (.ldf) in two different computers you can delete the log files from the bin Directory and make sure the .mdf properties->Copy to Output Directory ->Copy if newer that will copy the selected DB file and it's log to the bin Directory. !Alert- if your DB file has only changed in the bin Directory all the changes ill be discarded!

Answer by Vishal Saini for Entity Framework The underlying provider failed on Open

1. Search "Component Services" in Programs and Files
2. Go to Services
3. Find "Distributed Transaction Coordinator" Service
4. Right click and Restart the Service

You've just done a restart of the service and the code should run without errors

Answer by Ayaat Shifa for Entity Framework The underlying provider failed on Open

Possible solution is described in this Code Project tip:

As folks mentioned IIS user network service user credentials while trying to log in sql server. So just change the Application pool settings in your IIS:

1. Open Internet Information Service Manager
2. Click on Application Pools in left navigation tree.
3. Select your version Pool. In my case, I am using ASP .Net v4.0. If you dont have this version, select DefaultAppPool.
4. Right click on step 3, and select advanced settings.
5. Select Identity in properties window and click the button to change the value.
6. Select Local System in Built-in accounts combo box and click ok. That's it. Now run your application. Everything works well.

Answer by Rustem Mustafin for Entity Framework The underlying provider failed on Open

We had connection string in web.config with Data Source=localhost, and there was this error (MSSQL was on the same machine). Changing it to actual `DOMAIN\MACHINE' helped, somewhy.

Answer by Kevin B Burns for Entity Framework The underlying provider failed on Open

For me when that usually starts happening, I have to remote desktop into the service and at the minimum restart IIS. It usually starts popping up right after I deploy code. On a few rare occasions I have had to restart the SQL services and IIS. I wrote a batch script to take a param (1 or 2) and have it setup to either do a restart of IIS ( i.e. 1), or go full nuclear (i.e. 2).

Answer by Boney for Entity Framework The underlying provider failed on Open

Always check for Inner Exception if any. In my case Inner Exception turned out to be really helpful in figuring out the issue.

My site was working fine in Dev Environment. But after i deployed to production, it started giving out this exception, but the Inner Exception was saying that Login failed for the particular user.
So i figured out it was something to do with the connection itself. Hence tried logging in using SSMS and even that failed.

Eventually figured out that exception showed up for the simple reason that the SQL server had only Windows Authentication enabled and SQL Authentication was failing which was what i was using for Authentication.

In short, changing Authentication to Mixed(SQL and Windows), fixed the issue for me. :)

Answer by Daniel for Entity Framework The underlying provider failed on Open

I get this exception often while running on my development machine, especially after I make a code change, rebuild the code, then execute an associated web page(s). However, the problem goes away for me if I bump up the CommandTimeout parameter to 120 seconds or more (e.g., set context.Database.CommandTimeout = 120 before the LINQ statement). While this was originally asked 3 years ago, it may help someone looking for an answer. My theory is VisualStudio takes time to convert the built binary libraries to machine code, and times out when attempting to connect to SQL Server following that just-in-time compile.

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