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In my Unity project I am facing an unknown error and error of loading library files

when I load my unity project it is showing me the 2 errors because of which I can't run my project. The errors are:
Unknown error occurred while loading 'Library/Artifacts/22/22ec59139bb4d4489ae56859248015ff'.
...and:
Library\PackageCache\com.unity.test-framework#1.1.29\UnityEngine.TestRunner\NUnitExtensions\Runner\TestCommandBuilder.cs(65,31): error CS0246: The type or namespace name 'ImmediateEnumerableCommand' could not be found (are you missing a using directive or an assembly reference?).
If anybody will help me to understand these issues.
I am using unity version 2021.1.25f1 and editor for C# script is visual studio 2022

This would occur when the version of your com.unity.test-framework package does not match the version of Unity editor you are using. Basically, there is a mismatch somewhere. I recommend going to your Windows > Asset Manager editor window, find all test related packages, and try to update them or uninstall/reinstall.
The most common cause for this issue is when someone upgrades the version of Unity that they are using (or downgrades), but doesn't go to check the compatibility of existing packages with the new Unity version. It can happen for other reasons, so I am not saying for sure that you changed Unity versions. But more often than not, this will fix your issue.

Namespace name "Device" does not exist in the namespace

I have a problem using System.Device and can't find a solution
I'm developing a software and want to get the position of the device. By referencing the .NET Framework I want to use the GeoCoordinateWatcher.
In my code I included System.Device.Location and added two packages to the project (GeoCoordinate and System.Device.Location.Portable). While running and debugging the code in monodevelop no error occurs, but when I compile the code with mcs the error mentioned in the title occurs:
Namespace name "Device" does not exist in the namespace
Im using a RasPi for coding and compiling.
Any idea what the problem is?

System.Device is not supported by Mono:
https://github.com/mono/mono/tree/master/mcs/class

Unity 3D is not loading new references from MonoDevelop

I'm trying to create a new variable with:
public Text customText;
To use the type Text, I need to include:
using UnityEngine;
using UnityEngine.UI;
But this reference doesn't exist in my list of references on MonoDevelop.
I download it manually and added the reference manually; now I can use the Text type and import the UnityEngine.UI.
Well, here is the issue. When I compile my solution, on MonoDevelop I get this error:
Error: The compiler appears to have crashed. Check the build output pad for details. (Assembly-CSharp).
But on Unity3D I get the error:
Assets/UI/Scripts/HudController.cs(2,19): error CS0234: The type or namespace name `UI' does not exist in the namespace `UnityEngine'. Are you missing an assembly reference?
The dll UnityEngine is by default in the list of references, but not the UnityEngine.UI.
What I'm doing wrong?

I've faced this problem. Actually i've seen few solutions, but they helped me for only few launches of Unity.
Here is the links:
1) http://forum.unity3d.com/threads/unityengine-ui-dll-is-in-timestamps-but-is-not-known-in-assetdatabase.274492/#post-2015083 (post by j.robichaud)
2) http://answers.unity3d.com/questions/847994/unityeditorui-reference-missing.html
I hope any of it will help you.
In my case only reinstall was the cure. :)

Why am I getting the following error when compiling this assembly?

I'm attempting to use the following command line command to compile an assembly of the code from my project:
C:/"Program Files"/Unity/Editor/Data/Mono/bin/gmcs
-target:library -out:C:/Users/Austin/Desktop/PixelExpanse.dll
-recurse:C:/Users/Austin/Desktop/Projects/Repos/trunk/PixelExpanse/SpaceColonyRefactor/Assets/Source/*.cs
-d:RUNTIME -r:C:/"Program Files"/Unity/Editor/Data/Managed/UnityEngine.dll
As you can see, I am, I believe, correctly referencing the UnityEngine.dll.
The code that would be compiled contains references to UnityEngine.UI and UnityEngine.EventSystems. But when I run the above command, I get the following compile error:
error CS0234: The type or namespace name 'EventSystems' does not exist in the namespace 'UnityEngine'. Are you missing an assembly reference?
From what I have been able to find through googling, it SEEMS like an error people were getting when using a pre-4.6 assembly, because thats when EventSystems and UI were both introduced. But I don't know how I could be missing that in the dll I'm referencing as Unity 5 is the only version that has ever touched this computer.
As a side note, I have posted this question to Unity Answers and have yet to receive a response. I expect it's because assembly compilation is beyond the scope of what most users there choose to undertake. Hence my asking it here.

The namespace UnityEngine.EventSystems actually appears in UnityEngine.UI.dll and not UnityEngine.dll so it seems you need to reference the former too when compiling manually from the command-line. Unity projects have this by default (see below).
This is verified by opening up the assembly in your reflector tool of choice, here I am using JetBrains dotPeek:
This is how my test project appears with default Unity references. Note that by default a reference to UnityEngine.UI already appears in the Unity-created project:
When I built my Windnows desktop app via Unity, the above dlls appeared in:
<drive>:<projectOutFolder>\<projectName>_Data\Managed

You can try:
right click on "project panel", and after "Reimport All".
It's can be happen due to switch between platforms, e.g. IOS, or Desktop.. thus, folrders are deleted by became unecessary..
Solve for me: Unity 5.2, Win 7, 32bits;
Good luck!

I checked the UnityEngine.dll and the Eventsystems/UI namespace is not included. Despite, there is a dll in Unity5\Editor\Data\UnityExtensions\Unity\GUISystem\UnityEngine.UI.dll which includes these namespaces.

For mac, it's /Applications/Unity/Unity.app/Contents/UnityExtensions/Unity/GUISystem/UnityEngine.UI.dll.

Umbraco 5 - type or namespace 'AssemblyContainsPlugins' could not be found

I'm trying to create plugins for Umbraco 5. I see in all examples mention of the following line to AssemblyInfo.cs, in order to mark an assembly for export:
[assembly: AssemblyContainsPlugins]
Trouble I'm having is I receive the 'type or namespace' error for AssemblyContainsPlugins and AssemblyContainsPluginsAttribute. I tried googling the names to see what assembly I'm not referencing but can't find it.
Can anyone see what I've missed here?

Yes, you missed this using statement:
using Umbraco.Cms.Web;