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Visual Studio Intellisense Can Find References But Build Fails Due To Missing References

I'm currently running into an issue (on Visual Studio 2022) where the test project within my solution is referencing a few other projects in my solution; however, trying to build the test project results in errors for these project references. Even more interesting is that this test project used to be working fine.
So far I've:
Double checked the pathing of the project dll's being referenced
Removed and re-added the project references.
Editing the file, Intellisense is able to find the references, but when building the console output shows errors.
Cleaned the solution
Seen recommendations online of clearing the Temp folder and AppData\Local\Microsoft\VisualStudio\17.x\ComponentModelCache for my user account and have done so
None of this has helped. Any guidance on what to research or things to try/insight to the problem would be much appreciated!
Thank you
-Austin
EDIT 1 (7/5/2022)
Error List Image
The error seem to resolve themselves when I click on them from the Error Lists (after viewing the place in the file where the reference error is occurring, the error disappears after a few seconds, removing it from the Error List and also the removing the red squiggle underline). However, the error does not actually resolve as there are still the same reference errors when trying to Build the test project.
For example, STEP.Entities is a project in the solution that is referenced by the test project. However, the test project can't find the referred Entities project.

I realized the issue was caused by packages used in the other projects of the solution were targeting different .NET versions than the same packages within the Test project.
(Firstly, to determine this I went to Tools > Projects and Solutions > Build and Run > select MSBuild Project Build Verbosity as Diagnostic. (I believe this generates more a detailed report of the status to the Output Console when building projects)).
Specifically, a lot of these packages in my test project were targeting .NET v 4.8 as opposed to v4.7.2 being targeted by packages in the other projects, and the Test project itself and other projects targeting v4.7.2. I updated my Test project to target v4.8 and everything works/references can be found.

I've had this problem recently with a project from GitHub, my best sugestion is to try checking the version you are using and maybe select an older version of the said references.
It took me a while to get it done but it worked.

I think I worked around this with following global.json in the root of my drive:
C:\global.json
{
"sdk": {
"version": "6.0.300",
"rollForward": "latestFeature",
"allowPrerelease": false
}
}
Or there might be a global.json in your solution somewhere, with a .NET SDK version that doesn't exist...
To list all installed .NET sdks on your computer, run
dotnet --list-sdks
and pick the correct version.

This keeps happening - Microsoft.Data.SqlClient.resources.dll is not found during .NET Core 3.1 debug session in Visual Studio 2019

This keeps happening - Microsoft.Data.SqlClient.resources.dll is not found during .NET Core 3.1 debug session in Visual Studio 2019
Exception message:
"Could not load file or assembly 'C:\Users\user1\Dev\source\repos\repo_name\project_name\bin\Debug\netcoreapp3.1\runtimes\win\lib\netcoreapp3.1\Microsoft.Data.SqlClient.resources.dll'. The system cannot find the file specified."
It is only happening with this specific package, basically when I go to create a new SqlConnection object instance. Everything is working fine, except that some random software change on the system seems to always impact this package.
I'm stumped. Any ideas how to work around this in C#? It seems like it magically fixes itself if I repair or reinstall Visual Studio and .NET Core SDKs.

You can use nuget Packages to add System.data.SqlClient:
In the solution explorer /Dependencies/Packages
Search system.Data.SqlClient and add
Other investigation that could help you:https://social.msdn.microsoft.com/Forums/en-US/ec2361a3-1931-4423-bf68-08b206ce67aa/reference-systemdatasqlclient-not-found?forum=netfxbcl

Error when building a project which uses ZipDiff and SharpLibZib

I've been trying to use ZipDiff to compare two zip files. I installed ZipDiff through the NuGet Package Manager in Visual Studio which installed the necessary dependencies such "SharpZipLib" as well.
During the installation it was stated that the version of SharpZipLib has to be higher than or similar to 0.86 in order to use the latest version of ZipDiff. It was also mentioned that the SharpZipLib version which got downloaded was higher than 0.86. But when I tried to build the solution I get the following error.
Build error
Then when I checked the properties of the reference that was added, the version was "0.85..".
Properties Window
Then I reinstalled them and did it through the "Package Manager Console" but I got the same result.
Can someone tell me why this happens?

one or more projects require a platform SDK(UAP, 10.0.16299.91)

I am trying to open the UWP project but however because of versioning issue I am not able to load the project. It gives me following error.
However, this version is already installed and even I have tried to install it again. But even after that is again giving me the same error.
I have updated the project version in .csproj file also as below. The version which is mentioned in the screenshot is already installed.
<TargetPlatformVersion>10.0.16299.91</TargetPlatformVersion>
<TargetPlatformMinVersion>10.0.16299.15</TargetPlatformMinVersion>
After doing all this it still gives the error as Visual Studio Update Required.
Any help on this appreciated!

Don't try to target your project to 10.0.16299.91 from your csproj, you can specific the target version to 10.0.16299.0 as Jet suggested. The build version is different from target version.
Thinking about this, if your customer is on 10.0.16299.0, then he cannot use your app? This is not reasonable. By the way, when you load your project, it will asks you to retarget your project, you can find the supported target version listed there.

error APPX3212: SDK root folder for 'Portable 7.0' cannot be located

I'm trying to build my solution using TeamCity / MSBuild.
It's a WebAPI project which shares some entities in a PCL with a mobile client.
I see there are a few caveats around getting the PCL reference libraries installed on a buildserver, which I think I've sorted
(Building Portable Class Library Project in build server fails)
However, I'm getting an error during the build of the portable class library as follows:
[11:20:49][Doctrina.Pcl.Entities\Doctrina.Pcl.Entities.csproj] _GetSdkToolPaths
[11:20:49][_GetSdkToolPaths] GetSdkPropertyValue
*[11:20:49][GetSdkPropertyValue] C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v14.0\AppxPackage\Microsoft.AppXPackage.Targets(975, 5): error APPX3212: SDK root folder for 'Portable 7.0' cannot be located. See http://go.microsoft.com/fwlink/?prd=12560&pver=1.0&plcid=0x409&ar=MSDN&sar=PlatformMultiTargeting&o1=Portable&o2=7.0 for more information.*
The "help" link doesn't go anywhere useful and it seems to be very google-resistant in terms of finding any resolution.
I don't have Visual Studio 2015 installed on the build-server at all, but I have installed PortableClassLibrary tools, copied the reference directory from my local PC over, etc, as per the other related SO question.
Help please?

I encountered this error when attempting to build portable projects targeting .NET Standard.
I managed to resolve it without installing Visual Studio on my build server, by copying from a machine that does have Visual Studio installed:
C:\Program Files (x86)\Microsoft SDKs\Portable\v14.0
C:\Program Files (x86)\MSBuild\Microsoft\Portable
C:\Program Files (x86)\ReferenceAssemblies\Microsoft\Framework.NETPortable
I later attempted to build a WebApi project targeting .NET Core (this was an xproj file) and as soon as I added the XProj file to my solution, I had to also copy:
C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v14.0\DotNet
C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v14.0\DotNet.Web
That got me a bit further but it also caused other projects to stop building properly (that were working fine without the XProj file in the solution). One thing I noticed, the NuGet tooling for .NET Core does not support authenticated NuGet feeds, so I had to enable anonymous access on my feed. But now my .NET Standard project now fails with error MSB4057: The target "_GenerateDependencyFragmentJson" does not exist in the project.
I've yet to get around to diagnosing this, but I hope the above information helps someone. If you're not using xproj files and just trying to use .NET Standard projects, the above should be all you need to build without installing Visual Studio.
Just a side note, I tried really hard to avoid having to copy these files by first trying to install Microsoft Build Tools 2015 Update 3, hoping it would put the required files in place, but it did not sadly. I'm pinning my hopes on the next version of MSBuild that is being used in VS15, and hoping that it's build tools package will have everything required to build this stuff when it comes out, as it doesn't seem like they are updating the 2015 Build Tools with this support.