Unable to find the requested .Net Framework Data Provider. It may not be installed

问题

After completing the ASP.NET MVC 3 (find here), I tried to publish the app online. I contacted the hosting company to be sure if it's possible to host MVC 3 apps. But I had to bin deploy the (dll files) application. So after following some steps on hanselmans blog, I'm getting stuck on following error:

Unable to find the requested .Net Framework Data Provider. It may not be installed. 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.ArgumentException: Unable to find the requested .Net Framework Data Provider. It may not be installed.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[ArgumentException: Unable to find the requested .Net Framework Data Provider. It may not be installed.]
System.Data.Common.DbProviderFactories.GetFactory(String providerInvariantName) +1420503
System.Data.Entity.Internal.LazyInternalConnection.TryInitializeFromAppConfig(String name) +362
System.Data.Entity.Internal.LazyInternalConnection.Initialize() +49
System.Data.Entity.Internal.LazyInternalConnection.get_ConnectionHasModel() +10 System.Data.Entity.Internal.LazyInternalContext.InitializeContext() +265 System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType) +17
System.Data.Entity.Internal.Linq.InternalSet1.Initialize() +62
System.Data.Entity.Internal.Linq.InternalSet1.get_InternalContext() +15 System.Data.Entity.Infrastructure.DbQuery1.System.Linq.IQueryable.get_Provider() +37 System.Linq.Queryable.OrderByDescending(IQueryable1 source, Expression1 keySelector) +66
MvcMusicStore.Controllers.HomeController.GetTopSellingAlbums(Int32 count) +420 MvcMusicStore.Controllers.HomeController.Index() +47
lambda_method(Closure , ControllerBase , Object[] ) +40
System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +17
System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary2 parameters) +188
System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +27

Any help is appreciated.

回答1:

From my experience, that error means that the value of the providerName attribute on the connection string in your web.config is either incorrect, or the provider literally is not installed. If your providerName is set to System.Data.SqlServerCe.4.0 (SQL Server Compact), which is not uncommon in development, I can guarantee you that it's not installed on your web host; it's only used inside Visual Studio for development. You probably just need to change it to a the real SQL Server provider: System.Data.SqlClient.

回答2:

I resolved the issue.

I find a space in providerName. So, .net framework is not able to estblish connection string with database.

Check your connectionString tag attribute value. Your providerName may be not well defined. Look for any spaces (as the naming does not allow any) and check extra characters in providerName value.

回答3:

Another data point...

I work with Oracle and the Entity Framework. I installed the Oracle ODP.NET, Managed Driver to get by this problem. In the NuGet Package Manager enter

Install-Package Oracle.ManagedDataAccess

It will update the App.config with the appropriate assembly information and the DbProviderFactories. I'm using VS 2015, Entity Framework 6. I also have the Oracle Developer Tools installed.

回答4:

I faced the similar Issue .. and there is very funny solution for that .. Just look into your ConnectionString -- If it is same that you have used for your other ASP.Net apps, then it should not be... Entity Framework has a different case altogether

<add name="EmployeeContext" connectionString="Server=.\SQLEXPRESS;Database=DB1;User Id=user1;password=password1;" providerName="System.Data.SqlClient**;**" />

Change it to --

<add name="EmployeeContext" connectionString="Server=.\SQLEXPRESS;Database=DB1;User Id=user1;password=password1;" providerName="System.Data.SqlClient"/>

Can you identify the difference .. only one small -- There is no ';' at the end of ProviderName .. Yes and that makes the difference .. it should be same to same copy of the ProviderName, though I have not checked the case sensitivity. But that solved my Problem

回答5:

The error was perfect, and the comments above were good but in my case i literally spelled the provider wrong in the web.config file: System.Data.SqlClinet not System.Data.SqlClient

来源：https://stackoverflow.com/questions/16165158/unable-to-find-the-requested-net-framework-data-provider-it-may-not-be-install