The type initializer for 'System.Data.Entity.Internal.AppConfig' threw an exception

Question

I\'m working with EF5 in a MVC 4 aspnet website. Locally, everything works just fine, but when I publish it to the IIS and try to enter, I get the error

Answer 1

Change this part in your Web.config, according to the below code.(try this, it works to me.)

<entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="Data Source=.; Integrated Security=True; MultipleActiveResultSets=True" />   
      </parameters>
    </defaultConnectionFactory>
  </entityFramework>

Answer 2

I faced similar issue and changing defaultConnectionFactory to be SqlConnectionFactory helped me solve it.

Answer 3

Old question but it just happened to me for different reasons mentioned in the other answers, so I thought I'd share my findings.

In my case, the problem was how I defined my connection string entry in the app.config. I edited it directly in Notepad++ and I must have hit a shortcut, and minimized the entire string which I didn't spot, and started to get this error. This is how I was defined it:

<add name="MyDb" connectionstring="data source=MyServer;
 initial catalog=MyDatabase;integrated security=true" 
 providername="System.Data.SqlClient" />

The second I changed the following parameters

connectionstring to connectionString

and

providername to providerName

Note: The problem was highlighted immediately In Visual Studio but clearly this isn't ideal if you're on a client site!

Answer 4

I ran into this issue when I forgot to set my Connections.config file to "copy always"

BareMessage = "Unable to open configSource file 'Connections.config'."

Answer 5

Check the C-drive inside C:\inetpub\wwwroot and remove all unnecessary folders from it, else remove unnecessary host files or folders from IIS.

Answer 6

I had multiple providers specified in my web.config.

 <providers>
      <provider invariantName="MySql.Data.MySqlClient" type="MySql.Data.MySqlClient.MySqlProviderServices, MySql.Data.Entity.EF6" />
      <provider invariantName="MySql.Data.MySqlClient" type="MySql.Data.MySqlClient.MySqlProviderServices, MySql.Data.Entity.EF6, Version=6.9.6.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d"></provider>
    </providers>

I simply removed one of those and it worked.

I am using MySQL though, not TSQL