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Could not load file or assembly C# Console Application with Class Library

I've created a Class Library in C# .Net Framework 4.8, and in the solution I've also included a Console Application, same target.
I'm running both in a x64 configuration.
No errors on build.
I referenced the App in the Library, and when I run a Button in a Form in the Class Library I'm getting an error:
System.IO.FileNotFoundException: Could not load file or assembly
'ExampleApp, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' or
one of its dependencies. The system cannot find the file specified.
File name: 'ExampleApp, Version=1.0.0.0, Culture=neutral,
PublicKeyToken=null'
I've combed the internet and SO for a solution. I tried repairing Visual Studio, I tried deleting the .vs folder in the projects, I tried things like:
solution 1
and
solution 2
I seriously tried everything I could think of. It has to be something to do with the .dll dependencies imho, because the only one that my ExampleApp is using is the Microsoft.CognitiveServices.Speech reference which I installed via NugetPackage in my solution.
No idea how to debug this further or get a proper trace stack from this error...
Any ideas on how to proceed?
Thanks

Solved by changing the .dll's Copy Local property to True

Exactly #Yafim Simanovsky, I solved also my problem by changed <Private> flag to True.
My problem (“Could not load file or assembly…”) was with new Designer ‘WpfSurface.exe’ from VS 2022, which after changing the reference tags ‘Private’ to True, was able to copied all dependent .dll files to Cache.

.NET Framework dll Could not load file or assembly 'Newtonsoft.Json....'

I am creating a c# .net framework library (.dll) that will act as a plugin for another piece of software. I want to use the Newtonsoft.json library but when the I call the json library I get the classic "FileNotFoundException":
Could not load file or assembly 'Newtonsoft.Json, Version=12.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed' or one of its dependencies. The system cannot find the file specified.
The .dll is definitely being copied to the directory I am trying to run the plugin from. A lot of others have had this issue and I have tried everything I've seen (updating, reinstalling, etc.) but no luck yet. Because this is a class library I do not have an "app.config" file to play with binding redirects, so I haven't been able to try that.
I have very basic code right now, this package is the only external reference I am using. I've only been working on this today, only ever trying with Newtonsoft.Json version 12.0.2. It is weird to me that it appears VS is looking for 12.0.0.0, however. This is not an option to download. Similarly, I've tried downgrading to version 11.0.2, and then it gives me the same error saying it can't find version 11.0.0.0.

Even though your project may not have an .app config, you can still view the package references by unloading your project and viewing the .csproj file.
To try and force a direct reference to Newtonsoft.Json 12.0.2, you can add this snippet
<ItemGroup>
<PackageReference Include="Newtonsoft.Json">
<Version>12.0.2</Version>
</PackageReference>
</ItemGroup>
I would recommend removing any other references in your .csproj for Newtonsoft.Json as well

.Net Core deps file modification not reflected

I have a .NET Core project with many libraries as dependencies.
I wanted to change code in one of the library (a dll dependency) and wanted to run the project using the said new dll.
I changed the file version of the dll in the deps.json file but when i run the project using dotnet project.dll I see this exception thrown:
Application startup exception: System.IO.FileNotFoundException: Could not load file or assembly 'CuPletEngine, Version=16.0.229.1809, Culture=neutral, PublicKeyToken=null'. The system cannot find the file specified.
I made the change to deps.json file in order to force the application to to look for a different dll version.
Why would it still look for older version?
Please help.

Weird Error Upgrading ASP.NET MVC from 4 to 5

I'm converting my project from MVC 4 to MVC 5 (and .Net 4 to .Net 4.5.2, which is the real driver of the changes.)
When I run one of my pages I get this error (blank space added by me for easier reading)
[A]System.Web.WebPages.Razor.Configuration.HostSection cannot be cast
to [B]System.Web.WebPages.Razor.Configuration.HostSection.
Type A originates from 'System.Web.WebPages.Razor, Version=1.0.0.0,
Culture=neutral, PublicKeyToken=31bf3856ad364e35' in the context
'Default' at location
'C:\windows\Microsoft.Net\assembly\GAC_MSIL\System.Web.WebPages.Razor\v4.0_1.0.0.0__31bf3856ad364e35\System.Web.WebPages.Razor.dll'.
Type B originates from 'System.Web.WebPages.Razor, Version=3.0.0.0,
Culture=neutral, PublicKeyToken=31bf3856ad364e35' in the context
'Default' at location
'C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET
Files\studentportal3g\2204bad2\aece9b3b\assembly\dl3\ad80387c\91adbf51_fc73d101\System.Web.WebPages.Razor.dll'.
When I first saw this is though, Ah easy! Not so much :)
I've gone over every project and made sure it's version is upgraded to MVC 5 which has the 3.0.0.0 version of System.Web.WebPages.Razor.dll.
Clean rebuild, still get the error. No problem , I'll delete the cached temp files.
Clean rebuild, still get the problem. I go back, manually check each version of System.Web.WebPages.Razor.dll, in the references of each project that has a reference to it. I check my folder where I copy dlls to make references to them manually, it's not there.
If my solution doesn't' contain a copy of the DLL or a reference to the DLL, and I've manually deleted the cache folders in 'C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET
Files\studentportal3g...
Where is the old bad dll coming from? How do I fix this error? How do I prevent it happening again?
Thanks,
Eric-

Visual Studio is a great tool, but it doesn't always make the right choices when it comes to upgrading dependencies, nor does it support every possible option available in MSBuild. Whenever you find yourself in a bind such as this you should manually review and (if necessary) edit your .csproj file in order to resolve it.
The problem isn't that your file exists in the GAC or that it has not been installed by NuGet, the issue is most likely that one of your project files still has a reference to the old version of System.Web.WebPages.Razor version 1.0.0.0, and you need to find all references to it and change them to 3.0.0.0 accordingly.
Right-click on your project node in Solution Explorer and click Unload Project.
Right-click the project node again and click Edit <projectName>.csproj.
Search the file for references to System.Web.WebPages.Razor and update the version and the HintPath accordingly (as shown below). Make sure the HintPath you use actually points to an existing file.
Repeat these steps for all dependent projects in the solution (and any that are in DLLs that are not part of the solution).
Old Reference
<Reference Include="System.Web.WebPages.Razor, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
<Private>True</Private>
<HintPath>..\packages\Microsoft.AspNet.WebPages.1.0.20105.408\lib\net40\System.Web.WebPages.Razor.dll</HintPath>
</Reference>
Updated Reference
<Reference Include="System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
<Private>True</Private>
<HintPath>..\packages\Microsoft.AspNet.WebPages.3.0.0\lib\net45\System.Web.WebPages.Razor.dll</HintPath>
</Reference>
You should also go through the web.config and /Views/web.config files to ensure that they are not referencing any old versions of this assembly.
NOTE: If the above instructions don't solve your issue, the issue likely is outside of your solution. Most likely there is a 3rd party library that is referencing the old version of the file somewhere. If so, you could attempt to get an updated version of the DLL.
You may also want to check out this question.

It looks like the old DLL is in the Global Assembly Cache (GAC). The GAC is a place where you can store assemblies that can be referenced from several applications on the machine. Click here to read more about GAC.
Use the tool gacutil to update the assembly in the GAC.
The tool is located somewhere under "Microsoft SDKs" folder in Program Files. For me, it was located in
C:\Program Files (x86)\Microsoft SDKs\Windows\v10.0A\bin\NETFX 4.6.1 Tools\
Open cmd and navigate to the place where gacutil i stored. Then use it like this:
gacutil.exe -i [path to your assebly] -f.
The -i parameter is for indicating where your assembly is located. The -f parameter is used to force an update of the assembly, if it was already there.
Example
Say your DLL is located in
C:\temp\System.Web.WebPages.Razor.dll
Then you would run gacutil.exe -i "C:\temp\System.Web.WebPages.Razor.dll" -f

Could not load file or assembly 'Microsoft.Practices.EnterpriseLibrary.Common' or one of its dependencies

I have searched google for this and could not find the solution to the problem.
My Website references DAL (custom dll) which references Enterprise Library Data Access Components.
I have added the Enterprise Library from the NuGet Package Manager and when I try to build the Website this compilation error pops up:
Error 44 Could not load file or assembly 'Microsoft.Practices.EnterpriseLibrary.Common' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference
I have tried setting the Copy Local = True in the DAL for the Enterprise Library dlls and the dlls are transferred to the Bin directory of the website along with DAL dll, but still the error pops up.
Can anyone guide me on this....

The problem is that the DLL that you are using and the one that is referenced in your project are different. I'm not sure what the difference in the manifest is, but it could be version and/or public key.
You have a couple of things to try:
Open the properties for the DLL reference in your project and set Version Specific to false.
Remove the reference, delete the DLL from the bin folder, and re-add the reference.
You could also have a different/incorrect version in your GAC. In order to make sure that you are always using a specific, known version create an assemblies folder relative to your project directory, copy the dll to that directory, and add a reference to the DLL in the assemblies directory rather than one in GAC or elsewhere on your machine. This will ensure that only the specific version that you have targeted for the application will be used rather than any version that is updated on your machine at a later time.

NuGet CommonServiceLocator
Install-Package CommonServiceLocator

This dll is likely to be in the GAC on developer machines as part of some windows application installation (my best guesses are Visual Studio or SSMS).
That’s why we are likely to get warnings or errors on the build machine which we try our best to keep the GAC as clean as the production server’s.
To download the file manually, you can go to https://servicelocation.codeplex.com/
To fix the build warnings and errors, you simply need to run a NuGet command to install the CommonServiceLocation package. The package contains only this one dll file. Microsoft has released only 1 version (1.0.0.0) of this file since 2008. The file is fully compatible with all .NET versions and all Unity versions.

I was able to resolve this issue by removing from ALL the Logging references in the app.config file::
, Version=6.0.0.0, Culture=neutral, PublicKeyToken=null
ie:
<section name="loggingConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.LoggingSettings,
Microsoft.Practices.EnterpriseLibrary.Logging,
Version=6.0.0.0, Culture=neutral, PublicKeyToken=null"
requirePermission="true" />
Becomes:
<section name="loggingConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.LoggingSettings,
Microsoft.Practices.EnterpriseLibrary.Logging"
requirePermission="true" />
This is not ideal, but it does work...
The Enterprise Library Configuration Tool, sets the values back, so you need to watch for that. I know there is a way to tell the config file to accept these mis-matched settings -- but I I am not sure how.

Setting the PublicKeyToken values for each of the EnterpriseLibrary references in Web.Config fixed it for me.

Remove the reference, delete the DLL from the bin folder and VS, and re-add the reference.