Login failed for user 'IIS APPPOOL\ASP.NET v4.0'

Looks like it's failing trying to open a connection to SQL Server.

You need to add a login to SQL Server for IIS APPPOOL\ASP.NET v4.0 and grant permissions to the database.

In SSMS, under the server, expand Security, then right click Logins and select "New Login...".

In the New Login dialog, enter the app pool as the login name and click "OK".

https://i.stack.imgur.com/6sfIM.png

You can then right click the login for the app pool, select Properties and select "User Mapping". Check the appropriate database, and the appropriate roles. I think you could just select db_datareader and db_datawriter, but I think you would still need to grant permissions to execute stored procedures if you do that through EF. You can check the details for the roles here.

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https://i.stack.imgur.com/PcbL4.png

Under ApplicationPoolIdentity you will find local system. This will make your application run under NT AUTHORITY\SYSTEM, which is an existing login for the database by default.

Edit: Before applying this suggestion you should note and understand the security implications.

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I solved this problem using sql as following image.

Right click on db-> properties -> permission -> View Server permission -> and then select IIS APPPOOL\ASP.NET v4.0 and grant permission.

https://i.stack.imgur.com/uDola.png

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ensure you have...

Trusted_Connection=false;

in your connection String

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Run this sql script

IF NOT EXISTS (SELECT name FROM sys.server_principals WHERE name = 'IIS APPPOOL\DefaultAppPool')
BEGIN
    CREATE LOGIN [IIS APPPOOL\DefaultAppPool] 
      FROM WINDOWS WITH DEFAULT_DATABASE=[master], 
      DEFAULT_LANGUAGE=[us_english]
END
GO
CREATE USER [WebDatabaseUser] 
  FOR LOGIN [IIS APPPOOL\DefaultAppPool]
GO
EXEC sp_addrolemember 'db_owner', 'WebDatabaseUser'
GO

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If in the connection string you have specified:

User ID=xxx;Password=yyy

but in the connection string there is:

Trusted_Connection=true;

SQL Server will use Windows Authentication, so your connection values will be ignored and overridden (IIS will use the Windows account specified in Identity user profile). more info here

The same applies if in the connection string there is:

 Integrated Security = true;

or

 Integrated Security = SSPI;

because Windows Authentication will be used to connect to the database server. more info here

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go to iis -> application pools -> find your application pool used in application

https://i.stack.imgur.com/Eimtu.png

select your application pool used for the application right click select advanced settings

https://i.stack.imgur.com/He8s0.png

https://i.stack.imgur.com/mvs8V.png

select built in as Local System and click ok

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1_in SqlServer Security=>Login=>NT AUTHORITY\SYSTEM=>RightClick=>Property=>UserMaping=>Select YourDatabse=>Public&&Owner Select=>OK 2_In IIs Application Pools DefaultAppPool=>Advance Setting=>Identity=>LocalSystem=>Ok

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I hate the ApplicationPoolIdentity. I always set a Windows User Account as the account on AppPools.

As adrift says, it does sound like a database security issue. So create an NT user account, assign it to the ASP.NET v4.0 AppPool and then grant it permission on the website folder and to the relevant table(s) in SQL.

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First thing you need to clear if you are using windows authentication and you are not mentioning any username password in your connection string then:

What happens when you run your code through localhost: when you run your wcf test client from localhost, it will be able to communicate to database as local debug mode application is calling database by your account's service. So it has access to database because devenv.exe is running under your user account.

But when you deploy your web service in IIS. Now understand this service runs under IIS not under your account. So you need to assign access rights to IIS service to access the sql server for windows authentication. Here your web service would not be able to communicate to the SQL server because of access rights issue and Login Failed for user_______ (here your user will come)

So if you are using windows authentication to connect your database, you just have to change the IIS Application pool settings. You need to change IIS Application pool's identity to local System.

Below are the Steps for windows authentication WCF:

1) Open IIS (windows+R (run) then type inetmgr, then click ok)

2) double click your PC name under Connections

3) Click Application Pools

4) Select your app pool (DefaultAppPool)

5) Then under actions on the right click Advanced Settings:

6) Go to Process Model section and

7) click on Identity.

8) Now select LocalSystem.

Now open your sql server management studio: open run-> then type ssms ->then press ok In ssms, login using your windows authentication account. Open security tab expand logins tab then you will be able to view your account.

Now open properties of your account go to userMapping then select the database you want to connect then check the role membership services you want to use for the selected database. click ok.

(For network services i.e. intranet users you need to configure above settings for NT AUTHORITY\SYSTEM user too)

add Trusted_Connection=True; property in your connection string. Save it & deploy the web service. Restart app pool.

you will be able to connect the database now.

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I had to create a user `IIS APPPOOL\DefaultAppPool' as shown below in SQL Server. Security > Login > Right click and press 'New Login'. You only enter the username as show in red in the screen.

https://i.stack.imgur.com/x3MZV.png

Then go into that new user properties, check the database this user will access (marked in blue below) and select db_owner as well. I had to select because although connection was working but subsequent SELECT queries didn't had the access if this was not selected.

https://i.stack.imgur.com/Fq4Ta.png

These two should do it. Basically you are making the new user owner for the database so it has full access.

You don't need to restart SQL Server or anything, should work.

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Don't use Integrated Security. Use User Id=yourUser; pwd=yourPwd;

This solves the problem.

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I had this issue and it was actually caused by something different - I had the 'IIS APPPOOL\ASP.NET v4.0' user in my database but it still wasn't working.

I had recently upgraded my SQL Server Install and in the process the User had become disconnected from the Login - so there was an 'IIS APPPOOL\ASP.NET v4.0' under Database -> Security -> Users BUT no User not under Security -> Logins.

Added the Login 'IIS APPPOOL\ASP.NET v4.0' to Security -> Logins, SQL Server automatically mapped it to the User in the database (this used to have to be done manually) and problem fixed.

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I had this message and I use Windows Authentication on the web server.

I wanted the currently authenticated web user to be authenticated against the database, rather than using the IIS APPPOOL\ASP.NET v4 User specified in the App Pool.

I found by entering the following in the web.config fixed this for me:

<system.web>
  <identity impersonate="true" />
</system.web>

https://msdn.microsoft.com/en-us/library/bsz5788z.aspx

I see other Answers regarding creating the AppPool username in the SQL DB or just to use SQL Auth. Both would be correct if you didn't want to capture or secure individual Windows users inside SQL.

Tom

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I Have the same problem I solved it by changing Integrated Security=True to false now its working

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Setting the identity only makes this work in my pages.

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Cassini runs your website as your own user identity when you start up the Visual Studio application. IIS runs your website as an App Pool Identity. Unless the App Pool Identity is granted access to the Database, you get errors.

IIS introduced App Pool Identity to improve security. You can run websites under the default App Pool Identity, or Create a new App Pool with its own name, or Create a new App Pool with its own name that runs under a User Account (usually Domain Account).

In networked situations (that are not in Azure) you can make a new App Pool run under an Active Directory Domain user account; I prefer this over the machine account. Doing so gives granular security and granular access to network resources, including databases. Each website runs on a different App Pool (and each of those runs under its own Domain User account).

Continue to use Windows Integrated Security in all Connection Strings. In SQL Server, add the Domain users as logins and grant permissions to databases, tables, SP etc. on a per website basis. E.g. DB1 used by Website1 has a login for User1 because Website1 runs on an App Pool as User1.

One challenge with deploying from the Visual Studio built-in DB (e.g. LocalDB) and built-in Web Server to a production environment derives from the fact that the developer's user SID and its ACLs are not to be used in a secure production environment. Microsoft provides tools for deployment. But pity the poor developer who is accustomed to everything just working out of the box in the new easy VS IDE with localDB and localWebServer, because these tools will be hard to use for that developer, especially for such a developer lacking SysAdmin and DBAdmin support or their specialized knowledge. Nonetheless deploying to Azure is easier than the enterprise network situation mentioned above.

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If you have your connection string added in your web.config, make sure that "Integrated Security=false;" so it would use the id and password specified in the web.config.

<connectionStrings>
    <add providerName="System.Data.SqlClient" name="MyDbContext" connectionString="Data Source=localhost,1433;Initial Catalog=MyDatabase;user id=MyUserName;Password=MyPassword;Trusted_Connection=true;Integrated Security=false;" />
</connectionStrings>

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As pointed out, Do not use Windows Authentication, Use SQL Server Authentication

Also if you created connection using "Server Connection" dialog, make sure to check the connections in web.config. It is likely that you created/modified connection and it was stored as trusted connection in web.config. Simply use this authentication

<add name="MyDBConnectionString" connectionString="Data Source=localhost;Initial Catalog=Finantial;User ID=xxx;Password=xxx" providerName="System.Data.SqlClient"/>

which should fix the error.

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https://i.stack.imgur.com/Ti9Bs.png

Add New User with User Name and Login name as IIS APPPOOL\ASP.NET v4.0 with your default schema. Go to Owner schema and Membership, Check db_datareader, db_datawriter

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You can face this wrong in specific database which is created after SSMS update. Open SSMS and select your databases and open your required database then click Security--> Users--> and right click on Users and click again on 'New User' and add 'NT AUTHORITY\Authenticated Users' and save you work and go to your Form on Web/Desktop whatever do you. Enjoy....

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Thought I'd post this as an answer as it is relevant to the question and can answer it in some cases.

That same message appears also if the database does not exist!

Be sure your connection string has no misspellings, is pointing to the right server instance, etc.

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In Asp.net webform,

this error fixed when installing asp.net from:

Server Manager > Manage > Add Role and Feature > Server Roles > Web Server (IIS) > Web Server > Application Development > ASP.NET 3.5/4.6 is installed.

my problem fixed.

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something similar happened to me what worked for me was changing the property Integrated Security = True to Integrated Security = false in the web.config of the website

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go to iis -> application pools -> find your application pool used in application -> click it and then click 'Advance Settings' in Actions panel. Find 'Identity' property and change it to localsystem.

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Have you done what @Teddy recommended and you STILL get the same error?

Make sure you're changing the settings for the app pool that corresponds to your virtual directory and not the parent server. Each virtual directory has its own AppPool and doesn't inherit.

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In DefaultAppPool set NetworkService in the Identity property and in Sql Server add User Network Service and give it the appropiate permissions to your database, that's work very well for me, I've tested locally but I think this is the best configuration for connecting from any other computer in the network. when you set LocalSystem in the Identity in IIS that's work well and it is not necessary to create any other user in Sql Server but I think that will not work in a network environment.

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I ran into the same problem testing ASP.NET Web API

Developed Web.Host in Visual Studio 2013 Express Database created in SQL Server 2012 Express Executed test using built in IIS Express (working) Modified to use IIS Local (from properties page - web option) Ran test with Fiddler Received error - unable to open database for provider.... citing 'APPPOOL\DefaultAppPool'

Solution that worked.

In IIS

Click on application pool 'DefaultAppPool' Set Identify = 'ApplicationPoolIdentity' Set .NET framework = v4.0 (even though my app was 4.5)

In SQL Server Management Studio

Right click on Security folder (under the SQL Server engine so applies to all tables) Right click on User and add 'IIS APPPOOL\DefaultAppPool' In securables on the 'Grant' column check the options you want to give. Regarding the above if you are a DBA you probably know and want to control what those options are. If you are like me a developer just wanted to test your WEB API service which happens to also access SQL Server through EF 6 in MVC style then just check off everything. :) Yes I know but it worked.

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In case you add a new login, make sure that under server properties ( rightclick -> properties)/security, authentication mode is set to both sqlserver and windows not only windows.

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Add "Everyone" under security. If you added the Server and the users logging in to the database, then this is something you are missing. Hope this helps.

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