Unable to load System.Threading.Tasks.Extensions

Question

I have a web project build on .net framework 4.5.1. We are trying to added PostgreSQL support for the project. Using Nuget, I have installed 4.0.4 npgsql to the project. Under references, I see the following being added to the project.

1. Npgsql - 4.0.4.0 - Runtime version v4.0.30319
2. System.Threading.Tasks.Extensions - 4.2.0.0 - Runtime version v4.0.30319

When I tried run the project and connect and get the data from the database, I am getting the following error saying FileNotFoundException:

    System.TypeInitializationException       HResult=0x80131534       Message=The type initializer for 'com.rsol.RConfig' threw an exception.       Source=RConfig       StackTrace:        at com.rsol.RConfig.getInstance() in C:\Workspaces\PS\RConfig\RConfig.cs:line 1113        at RAdmin.Global.Application_Start(Object sender, EventArgs e) in C:\Workspaces\PS\RAdmin\Global.asax.cs:line 528      Inner Exception 1:     TypeInitializationException: The type initializer for 'com.rsol.Db.DbMgr' threw an exception.      Inner Exception 2:     FileNotFoundException: Could not load file or assembly 'System.Threading.Tasks.Extensions, Version=4.2.0.1, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51' or one of its dependencies. The system cannot find the file specified.      Inner Exception 3:     FileNotFoundException: Could not load file or assembly 'System.Threading.Tasks.Extensions, Version=4.2.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51' or one of its dependencies. The system cannot find the file specified. 

System.Threading.Tasks.Extensions which is installed using Nuget is not getting loaded to the project. When I checked the properties of System.Threading.Tasks.Extensions reference, the dll file exists in the location. I have also tried installing System.Threading.Tasks.Extensions.dll file to assembly using gacutil. I am still getting the same error.

Please let me know if you need any additional information.

Any help is really appreciated.

Answer 1

In my case, I got the issue after upgrading to version 4.5.4 and tried @user2713341 answer. It didn't work but put me in the right direction.

My project had no bindings for this library, so I added the binding and it worked

<dependentAssembly>   <assemblyIdentity name="System.Threading.Tasks.Extensions" publicKeyToken="cc7b13ffcd2ddd51" culture="neutral" />   <bindingRedirect oldVersion="0.0.0.0-4.2.0.1" newVersion="4.2.0.1" /> </dependentAssembly> 

and it worked.

Note that it should be 4.2.0.1 even though the version is 4.5.4.