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

Question

Edit 2:

This does not happen when I use SQL Server. It only happen when I use Oracle. There has been a suggestion to debug or to provide inner exception for this. Yet, since this exception happen during the scaffolding, I can't get the inner exception. Also, I am not sure if we can debug a scaffolding process. If there is anybody who knows how it can be done, please let me know.

Error

There was an error running the selected code generator:

'Exception has been thrown by the target of an invocation'

Ok, firstly, the search results for this error seems to return many links.

And thus I learned that this error is not exclusive to creating Controller scaffolding in EF 6.

But my case is when I am about to create Controller Scaffolding using EF 6 in VS2013, when I create MVC web application.

The option I use is:

MVC 5 Controller with views, using Entity Framework

I use Oracle Database and Oracle.ManagedDataAccess namespace. Some relevant posts I found are these:

But none of them talking about the specific case for Oracle DB

But since they are talking about any DB in general, I nevertheless try some of their solutions, including:

Removing all sections, connectionStrings, and providers such that each of them only contain single item:

 <configSections>
   <section name="oracle.manageddataaccess.client" type="OracleInternal.Common.ODPMSectionHandler, Oracle.ManagedDataAccess, Version=4.121.2.0, Culture=neutral, PublicKeyToken=89b483f429c47342" />
 </configSections>

 <connectionStrings>
   <add name="EmployeeContext" connectionString="metadata=res://*/Models.EmployeeDataModel.csdl|res://*/Models.EmployeeDataModel.ssdl|res://*/Models.EmployeeDataModel.msl;provider=Oracle.ManagedDataAccess.Client;provider connection string=&quot;DATA SOURCE=VSDB;PASSWORD=mypassword;USER ID=myuser&quot;" providerName="System.Data.EntityClient" />
 </connectionStrings>

 <providers>
   <provider invariantName="Oracle.ManagedDataAccess.Client" type="Oracle.ManagedDataAccess.EntityFramework.EFOracleProviderServices, Oracle.ManagedDataAccess.EntityFramework, Version=6.121.2.0, Culture=neutral, PublicKeyToken=89b483f429c47342" />
 </providers>

Change DbSet in the Context to IDBSet

 public virtual DbSet<Employee> Employees1 { get; set; }

Use VS2013 with update 5.
Upgrade to Entity Framework 6.1.3

Changing the defaultConnectionFactory from:

 <entityFramework>
   <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
     <parameters>
         <parameter value="mssqllocaldb" />
     </parameters>
   </defaultConnectionFactory>
 </entityFramework>

to

 <entityFramework>
   <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
     <parameters>
         <parameter value="v11.0" />
     </parameters>
   </defaultConnectionFactory>
 </entityFramework>

Change OnModelCreating event handler from:

 protected override void OnModelCreating(DbModelBuilder modelBuilder) {
     throw new UnintentionalCodeFirstException();
 }

to

 protected override void OnModelCreating(DbModelBuilder modelBuilder) {
     base.OnModelCreating(modelBuilder);
     modelBuilder.HasDefaultSchema("myschema");
 }

But none of those works. I still get the same error. I even try all of them together and the problem still persists.

I have no more idea on what should be done in this case. Any idea?

Edit:

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. I am new with both web programming and Entity framework and really have no idea on what is going on behind the scene which causes the error.

Edit 2:

I have tried to isolate the problem by trying to redo the scaffolding by SQL server as suggested by Steve in the comment and Squiggle in the chat and I got no issue at all. So, the problem must have something to do with Oracle DB settings or (maybe) with the ODP.Net tool which I use Oracle.ManagedDataAccess - whether this is supported by EF.

Is there any other message or inner exception on the error? Target of an invocation is extremely broad (as you've found). — Steve, Feb 23 '16 at 01:54
@Steve the thing is, I cannot debug the inner exception since it is not a code - but a scaffolding, gotten from creating Controller by `MVC 5 Controller with views, using Entity Framework`. If there is any way to debug the inner exception for scaffolding, I would like to know too.. — Ian, Feb 23 '16 at 01:56
So you get it when you *create* the controller using Visual Studio tools? Hmm...Obvious question, but have you tried it in a new solution, or a different database access type? — Steve, Feb 23 '16 at 01:58
@Steve "when you create the controller using Visual Studio tools" yes, it is as you say... If you know how to debug such case, I would like to know how. I do it following a lecture shown in the youtube video series: https://www.youtube.com/watch?v=-pzwRwYlXMw&list=PL6n9fhu94yhVm6S8I2xd6nYz2ZORd7X2v at least in the video, there is not problem when using `SqlClient` default database. As for using `Oracle.ManagedDataAccess`, I have to do some configuration to make it work, and now I am stuck in this issue - not sure what configuration I left out. — Ian, Feb 23 '16 at 02:02
Perhaps you can try to comment out some code in your data context class, e.g. the dbset properties and check whether at some point the error disappears. — Martin, Feb 25 '16 at 15:25
@Martin thanks for the suggestion. I have more or less done it as I try to configure my project but to no avail. Nevertheless, I will try and see again. — Ian, Feb 25 '16 at 15:57

Pranav Singh · Answer 1 · 2016-02-29T10:37:48.983

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.

score 1 · Answer 2 · edited Jan 30 '18 at 20:03

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:

EF 6 from Nuget
Oracle.ManagedDataAccess v12.2.1100
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> -->

score 0 · Answer 3 · answered Oct 22 '18 at 17:02

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.

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

3 Answers3