BuildTasks.Csc task could not be loaded from the assembly?

Question

I feel guilty asking a question like this around here, but I'm at a loss and would appreciate some help.

A proof-of-concept like web application was built on one PC and put up on a repo to download on another PC at a different location. There was originally an auto-build feature set up where Azure would build and publish automatically on check-in, but that was removed. Things were working on both ends until one side included a bulk of excluded changes. Now I'm seeing the following error:

The "Microsoft.CodeAnalysis.BuildTasks.Csc" task could not be
loaded from the assembly ...\packages\Microsoft.Net.Compilers.1.0.0\build..\tools\Microsoft.Build.Tasks.CodeAnalysis.dll. Could not load file or assembly 'file:///...\packages\Microsoft.Net.Compilers.1.0.0\tools\Microsoft.Build.Tasks.CodeAnalysis.dll' or one of its dependencies. The system cannot find the file specified. Confirm that the declaration is correct, that the assembly and all its dependencies are available, and that the task contains a public class that implements Microsoft.Build.Framework.ITask.

Does anyone have any suggestions on where to begin looking for the issue?

Answer 1

It turns out that NuGet packages were committed to the repository and breaking everything. Deleting the project\project\packages directory from the repo solved all build problems since NuGet fetches the packages automatically on build.

Answer 2

I got this error when I created a new branch for my project.

It drove me crazy for an hour. I tried most of the suggestions over the internet including the accepted answer to this question.

I then closed the project, opened it again, cleaned it and the error is gone. So this means this could be cache issue.

Anyways, just wanted to share.

Answer 3

I too tried the top answer with no luck so deleted the contents of my bin and packages dir, closed and re-opened VS and everything fine now.

Answer 4

I have tried all solutions described before, but none worked.

What solved it for me, was to update the Microsoft.Net.Compilers from the NuGet Package Manager

Answer 5

• Right-click on your solution.
• Go to Manage Nuget Packages.
• Search for Microsoft.Net.Compilers.
• Install or update on dependent projects as necessary.

Answer 6

Re-build, clean solution and restart Visual Studio worked for me.

Answer 7

Deleting the package and cleaning the solution solved it for me.

Answer 8

Deleting these three directories solves the problem.

• /packages
• /bin
• /obj

NOTE: delete both /bin and /obj from all projects included in the solution (including Test projects).

Answer 9

Use the below step:

1) Delete the package folder.
2) close the visual studio.
3) open the project and rebuild the project.

Answer 10

Problem hides on TFS, you need to remove folder TestProject...\packages from TFS, check in, delete it from your local dir and build again. Worked!

Answer 11

I delete all from packages folder and rebuild solution. It's worked for me.

Answer 12

In my case: this works for me.

It turns out my teammate had already started looking into Windows 10 development and had Microsoft Build Tools 2015 installed on his machine.

I installed the software from https://www.microsoft.com/en-us/download/details.aspx?id=48159 and the problem was solved.

Answer 13

In my case, the solution was:

Use Windows Explorer and navigate to the offending path: C:\MyApplication\Code\Main\ABCProject\ABCProject.UI\Bin

Right click on bin folder > select properties > Uncheck ReadOnly.

Answer 14

In my case, the solution was:

1. Right Click on Solution.
2. Go to Manage Nuget Packages for this Solution.
3. Search for Microsoft.CodeDom.Providers.DotNetCompilerPlatform.
4. Uninstall the searched Package.
5. Restart the Visual Studio.

Answer 15

I just tried this on a clean install of a Windows 10 machine and the issue for me ended up being that I didn't have the .NET 3.5 framework installed. This stackoverflow question helps explain why.

Cannot build WIX project on windows 10

Answer 16

Right Click on Solution. Go to Manage Nuget Packages for this Solution. Search forMicrosoft.Net.Compilers on Browse Section.

Answer 17

Deleting the bin folder worked for me

Answer 18

In vs2017 community there appeared a new item in the "build" menu. It disappeared after I used it and was called something like "Optimise project build packages". I clicked it and it fixed everything, just restart etc. I did it on two machines.

What it did was removed Microsoft.net.compilers 2.10.0 and replaced with Microsoft.CodeDom.Providers.DotNetCompilerPlatform 2.0.1

So there you go - more automagic...

Answer 19

My project was built with .Net Core 2.2 but I had .Net core 3.0 preview installed. I uninstalled .Net Core 3.0 from my system and went through all my class libraries, removing Microsoft.Net.Compilers 3.0, then rebuilt and it worked.

Answer 20

I moved my solution from one drive to another, and one of the files could not be copied because "in used", for which I click ignored, producing the error described in this post. Copying the missing file manually fixed it.

file: Microsoft.Build.Tasks.CodeAnalysis.dll Destination directory: packages\Microsoft.Net.Compilers.2.1.0\tools

Answer 21

For me I was trying to open a MVC5 project in VS 2013 and I was getting this error, Opened it in VS 2017 and up it worked just fine.