How to Debug and to Fix 'Exception has been thrown by the target of an invocation' for EF 6, Oracle DB, Controller Scaffolding

I am not sure about the real issue in scaffolding but I want to add help to

"I would also be happy to know if someone can tell me how can I "debug" what's wrong with the scaffolding for my case to get the right solution for my case. "

Every .net web project has single entry point Global.asax that can handle all unhandled exceptions.

Make sure you don't have customErrors to Offin Web.config files.

Just add Application_Error method in Global.asax like:

void Application_Error(object sender, EventArgs e){ ... }

Better implementation is available at MSDN Link:

void Application_Error(object sender, EventArgs e){  // Code that runs when an unhandled error occurs  // Get the exception object.  Exception exc = Server.GetLastError();  // Handle HTTP errors  if (exc.GetType() == typeof(HttpException))  {    // The Complete Error Handling Example generates    // some errors using URLs with "NoCatch" in them;    // ignore these here to simulate what would happen    // if a global.asax handler were not implemented.      if (exc.Message.Contains("NoCatch") || exc.Message.Contains("maxUrlLength"))      return;    //Redirect HTTP errors to HttpError page    Server.Transfer("HttpErrorPage.aspx");  }  // For other kinds of errors give the user some information  // but stay on the default page  Response.Write("<h2>Global Page Error</h2>\n");  Response.Write(      "<p>" + exc.Message + "</p>\n");  Response.Write("Return to the <a href='Default.aspx'>" +      "Default Page</a>\n");  // Log the exception and notify system operators  ExceptionUtility.LogException(exc, "DefaultPage");  ExceptionUtility.NotifySystemOps(exc);  // Clear the error from the server  Server.ClearError();}

You can catch/watch unhandled exception here with all inner exceptions here.Hope it help in debugging the issue.

The most errors occurs due a bad configuration, for instance: connection strings, providers and so on.

In my case figured out that the issue was caused because when installed Oracle client, I clicked to configure it on machine.config so the configuration was taken from there.

Therefore, I deleted the oracle configuration from machine.config , after that the scaffolding working as we expected.

Installed:

1. EF 6 from Nuget
2. Oracle.ManagedDataAccess v12.2.1100
3. Oracle.ManagedDataAccess.EntiyFramework v12.2.1100

Removed from machine.config:

<!-- <section name="oracle.manageddataaccess.client" type="OracleInternal.Common.ODPMSectionHandler, Oracle.ManagedDataAccess, Version=4.122.1.0, Culture=neutral, PublicKeyToken=89b483f429c47342" /> --><!-- <oracle.manageddataaccess.client> -->    <!-- <version number="4.122.1.0"> -->      <!-- <settings> -->        <!-- <setting name="tns_admin" value="c:\oracle64\client\laralal\product\12.2.0\client_1\network\admin" /> -->      <!-- </settings> -->    <!-- </version> -->  <!-- </oracle.manageddataaccess.client> -->

I was getting this exact error attempting to scaffold using my oracle db but had no problem scaffolding to my SQL db. What I found was there was a version # discrepancy in the oracle.manageddataaccess.client sections of the machine.config file versus the web.config file. So I commented out every section in the machine.config file that contained "oracle.manageddataaccess.client", rebuilt my application and I was able to scaffold my controller and views successfully.