Cannot add a MVC controller VS2012 gives "object reference not set to an instance of an object"

Question

I have searched extensively and cannot find another person on the planet with this problem...
The symptoms are:
In Visual Studio 2012, on a MVC 4.0 Project that was upgraded from VS2010 and is configured for dual version editing from VS2012 and VS2010. When I right-click on the Controllers Folder and select Add->Controller... from the context menu, I get an "Object reference not set to an instance of an object" error from Visual Studio.

The existing code in the project runs fine, and if I use the Add->New Item option instead, and pick the Controller from the dialog box, then I can add a blank controller. I just cannot add a typed controller using the method above.

If I however create a new MVC4 Project, then I can add typed controllers again using the same menu, so the problem does not exist in Visual Studio's installation, it has to exist in the Project File.
I have also checked the references between my project and a new MVC Project and all the new project references are included in my project.
Has anyone experienced something similar?

How do I fix this?

Answer 1

I'm running VS 2019 Enterprise, ASP.NET Core 3.1.3.

I was trying to add MVC controller with views using Entity Framework (EF) after scaffolding in database first approach.

I run on this issue because one of the tables in my ER model was missing primary key.

That table was connected to table for which I tried to generate MVC controller through another table that has primary key so I didn't noticed initially that error.

Answer 2

This problem manifested on a target MVC5 project using VS2017.

Like the original op, a new project was attempted to perform an Add Controller with EF scaffolding against ApplicationUser. The error did initially manifest until a single user was registered forcing the database to be created. After that, add scaffolding worked without incident. I think this makes sense because the entity didn't really yet exist before the first registration, although I will stand corrected if someone more knowledgeable than myself has a more accurate explanation. But because Add Controller worked with a new project, just as the original op determined, it didn't seem to be a VS2017 installation problem. This pointed to something wrong with the taret project.

At this point in the target project an Undo All in Team Explorer was executed to get the project back to a previously working point. While this might be accomplished by getting a specific version, for this target project all that was required was an Undo All. A word of caution: in the case of this specific project, before undoing, the Package Manager was used to rollback the database to the starting point that would match with the Undo All. If one performs a get specific version, be sure to check if the database needs to get rolled back to the proper configuration. After resetting all the project changes, the object reference not set to an instance of an object error was no longer present during the Add Controller operation, fixing the error within the target project.

I post this response somewhat reluctantly because I am unable to duplicate the error, and I am unsure of what actually caused the problem in the first place, but this is a particularly nasty error if one is in the middle of a project and Add Controller starts failing. I figured if someone has this problem and rolling back the current change set might fix it for them, like me they will be thankful. If I later determine the pattern of activity that caused the problem to crop up in the first place, I'll surely add more to this post.

Answer 3

I had this problem on VS2012 on Win8, We where working on a project that we started developing on VS2010 and i wasn't able to create new controllers with the CTRL+M, CTRL+C shortcut.

Opening any project and re-installing MvcScaffolder and its dependencies under Manage Nuget package have fixed this for me.

Didn't have to restart VS2012 at all.

Answer 4

I had the same problem, im using database first, and it was because i have changed the .edmx contex.tt to generate the contex.cs with the connection name set to a custom method,

: base(sqlHelper.getMainConnectionString())

every time, before i change/update the .edmx, i need to change the connection name to it's creation defaults:

: base("name=YourWebconfigConnectionstringName")

rebuild the project and it works again

Answer:

Check your connectionstring string and provider parameters at the webconfig, then delete and recreate the .edmx this will force the generator to rebuild all the database objects, metadata included OR delete all tables in the designer, change the contex.cs to the default creation name, rebuild the project, add the tables, rebuild the project, it shoul work again.

Answer 5

The preferred answer of installing the Windows Management Framework 3.0 did not work. The download "Windows6.1-KB2506143-x86.msu" did not work on my Windows 7 32 bit system. It failed with the error "The update is not applicable to your computer".

Reinstalling MVCscaffolding with Manage Nuget Packages did not work.

My ProjectType GUID was correct.

Microsoft Web Developer Tools was already installed.

Deleting and recreating the solution didn't work.

It was necessary to repair the Visual Studio 2012 installation from the install disk to fix this issue.

Answer 6

The update Windows6.1-KB2506143-x64.msu worked for me. The problem started after a full SpyWare software scan. I think that it removes more things than the usual. So, back to normal life.

Answer 7

The issue seems to have been caused by an incomplete install/registration of the MvcScaffolder package. The following process resolved my issue for me.

Start Visual Studio and open the project. Open the Package Manager Console. (This was the "trick" or missing piece of information that led to the solution...)

Here I saw the following error caused by the PowerShell script used for registration:

New-Object : Could not load file or assembly 'System.Management.Automation, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.
At <ProjectPath...>\packages\MvcScaffolding.1.0.9\tools\registerWithMvcTooling.ps1:163 char:27
+     $newProvider = New-Object <<<<  $powerShellScaffolderProviderType($mvcScaffoldingProvider)
    + CategoryInfo          : NotSpecified: (:) [New-Object], FileNotFoundException
    + FullyQualifiedErrorId : System.IO.FileNotFoundException, Microsoft.PowerShell.Commands.NewObjectCommand

When I checked the registered scaffolders from the Package Manager Console I got:

PM> get-defaultscaffolder

DefaultName          ScaffolderName
Action               MvcScaffolding.Action
Controller           MvcScaffolding.Controller
CustomScaffolder     T4Scaffolding.CustomScaffolder
CustomTemplate       T4Scaffolding.CustomTemplate
DbContext            T4Scaffolding.EFDbContext
Mailer               Mailer.Razor
Repository           T4Scaffolding.EFRepository
UnitTest             MvcScaffolding.ActionUnitTest
View                 MvcScaffolding.RazorView
Views                MvcScaffolding.Views 

So clearly the scaffolders are configured to use the MvcScaffolding package, but the package had a registration error.

A quick search for the error provided this link http://mvcscaffolding.codeplex.com/discussions/437692 which refers to https://visioautomation.codeplex.com/discussions/397034 that suggests installing PowerShell 3, which is actually part of the Windows Management Framework 3.0, available from http://www.microsoft.com/en-us/download/details.aspx?id=34595. I picked the Windows6.1-KB2506143-x64.msu file when prompted because I’m running Win 7-64-bit.

Restart the PC after installation, re-open Visual Studio and the project and look at the Package Manager Console. If the error is gone, then so is the controller problem.

Answer 8

Installing "Microsoft Web Developer Tools" fixed this for me. Related:

How do I open a csproj with ProjectTypeGuids 349c5851-65df-11da-9384-00065b846f21?

• {E3E379DF-F4C6-4180-9B81-6769533ABE47} - MVC4 Project
• {fae04ec0-301f-11d3-bf4b-00c04f79efbc} - CSharp Project
• {349c5851-65df-11da-9384-00065b846f21} - Web Application Project (this is what you need web dev tools for)

Answer 9

Maybe your existing project have wrong ProjectTypeGuids element in .csproj file? Right one for MVC4 is {E3E379DF-F4C6-4180-9B81-6769533ABE47}.

Try to compare what project type do you have in new project and in your existing project.