May I get help resolving Package reference for .NET 4.7.2 Project?

2/3 of projects in a solution I have is running on .NET 4.7.2, the other project is a reactJS project running on .NET Core. The other two run well except one of the .NET 4.7.2 projects which seem to be trying to call packages that are not compatible with the project. The file it keeps hanging up on is the System.Threading.Tasks.Extension. The current version it is stuck on running is 4.5.2, of which I cannot downgrade and seems to not be compatible with .NET 4.7.2. I noticed that from the build logs. Here one line from the output file which seems to stand out to me:

Unified Dependency "System.Collections, Version=4.0.11.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a".

Using this version instead of original version "4.0.0.0" in "C:\project\packages\System.Threading.Tasks.Extensions.4.0.0\lib\portable-net45+win8+wp8+wpa81\System.Threading.Tasks.Extensions.dll" because there is a more recent version of this framework file. Resolved file path is "C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.7.2\Facades\System.Collections.dll".

(ResolveAssemblyReferences target) -> C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\MSBuild\15.0\Bin\Microsoft.Common.CurrentVersion.targets(2110,5): warning MSB3277: Found conflicts between different versions of "System.Threading.Tasks.Extensions" that could not be resolved. These reference conflicts are listed in the build log when log verbosity is set to detailed.

When the browser comes up this error is shown:

Could not load file or assembly 'System.Threading.Tasks.Extensions' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

I have been looking around at solutions which include meddling with the .csproj, web.config or package.config and not successful.

My goal is to have the project run successfully and resolve this conflict. Any help in resolving this issue would be greatly appreciated.

This was resolved by cleaning out all the packages and readding one by one.