Error 500

Apr 19 at 8:40 PM
I just did a fresh install of Server 2012 R2 and SQL Express 2014, followed all the steps but still receiving
500 - Internal server error.
There is a problem with the resource you are looking for, and it cannot be displayed.
Any idea?

this is my config file inside \AppConfig folder
  <add name="KbVaultEntities" 
       connectionString="metadata=res://*/KBVaultEntityModel.csdl|res://*/KBVaultEntityModel.ssdl|res://*/KBVaultEntityModel.msl;provider=System.Data.SqlClient;provider connection string=&quot;data source=MYSERVERNAME\KBVAULT;initial catalog=kbvault;integrated security=True;multipleactiveresultsets=True;application name=EntityFramework&quot;" 
       providerName="System.Data.EntityClient" />