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CefSharp - Could not load file or assembly 'CefSharp.Core.dll' or one of its dependencies

I've been working on a CefSharp WinForms app for a few weeks and I've had no issues with it. This morning, while adding a few things to the application, I tried to run it to test something and got the below error:
System.IO.FileNotFoundException was unhandled Message: An unhandled
exception of type 'System.IO.FileNotFoundException' occurred in
mscorlib.dll Additional information: Could not load file or assembly
'CefSharp.Core.dll' or one of its dependencies. The specified module
could not be found.
After searching for a while I found this:
https://github.com/cefsharp/CefSharp/wiki/Frequently-asked-questions#Runtime_dependencies
I checked bin/Debug/x86 for the project and all of the dependencies appear to be present. More importantly, it had been working fine five minutes earlier, and I didn't touch anything beyond a single class for an Entity Framework migration.
I've tried cleaning and rebuilding the solution, restarting Visual Studio, restarting my PC, and clearing out /bin/Debug, and none of these have helped.
Why would this error appear now after several days without it, and how can I resolve the issue?
Edit: I've done some further experimenting and I'm able to get the application to run in Release mode but not Debug mode. If I change the output path of Release mode to Debug, it fails with the same error (likewise, it succeeds in Debug with the Release output path).

First, make sure you installed the Microsoft Visual C++ Redistributable:
Version v93 and above: use Microsoft Visual C++ 2019 Redistributable or greater
Version v65 - v92: use Microsoft Visual C++ 2015 Redistributable or greater
Older Versions: use Microsoft Visual C++ 2013 Redistributable (exact version)
You could download the Visual C++ Redistributable from Microsoft. See C++ binary compatibility between Visual Studio versions for more detail on the version compatability.
Make sure to match the correct architecture, if your application is x64, you need to install the x64 build of Visual C++ Redistributable. Likewise if your application is x86 then you need to install the x86 build of Visual C++ Redistributable.
The Microsoft Visual C++ Redistributable depends on the Universal CRT. The Universal CRT is included as part of Windows 10/11. On older versions of Windows the Visual C++ Redistributable will install the Universal CRT.
For those wishing to include the Visual C++ Runtime with their application it's technically possible to include the runtime with your application. See also Local Deployment section of the Deployment in Visual C++ article from Microsoft.

I had the same problem until I installed the following redistributable:

SuperBerry's solution of installing VC++ redistribution package solved the problem for me. I'll just provide a little troubleshooting insights from my naïve perspective.
The error message is pretty clear, either the assemble CefSharp.Core.dll is missing or one of it's dependencies. So the question boils down to how do you figure out what is missing?
So first, do you have CefSharp.Core.dll? In the Solution Explorer look at the references for the project that is having this problem. You should find a reference to CefSharp.Core. If you can't find one, you're missing that assembly. If you have one, then the problem is that you're missing one of its required dependencies. When you click on the CefSharp.Core reference, in the detail, you'll get the full path to where it's located. In my case, it was in located at 'C:\Users\tom\source\repos\MyProject\src\packages\CefSharp.Common.41.0.0\CefSharp\x86\CefSharp.Core.dll'.
You then need to get a list of the CefSharp.Core dependencies to figure out which dependency your missing. Dumpbin.exe is a command line tool that you can use to get a list of dependencies. In order to use dumpbin, you need to make sure that it can be found on the path in your system environment variables. I found on the path of the VC Tools bin directory. In my case, I found one at: 'C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.25.28610\bin\Hostx64\x64'. Open a Command Prompt terminal and navigate to the folder containing CefSharp.Core.dll and key in the following:
>dumpbin /dependents CefSharp.Core.dll
the result I got was:
Dump of file CefSharp.Core.dll
File Type: DLL
Image has the following dependencies:
KERNEL32.dll
MSVCP110.dll
MSVCR110.dll
libcef.dll
USER32.dll
mscoree.dll
Not having worked with Microsoft Visual Studio for a number of years, I had to try and figure out where those dependencies are suppose to be located so that they can be resolved. I simply did an internet search such as "where is Kernel32.dll located" doing that for each dll until I found the missing dll. In my case, I could not find MSVCR110.dll, so I strongly suspected that was my problem. I then did an internet search for "MSVCR110.dll is missing" and found out that it was part of the vc++ redistribution. (SuperBerry, you were right on your first point). I also found that it could be downloaded from: 'https://www.microsoft.com/en-us/download/details.aspx?id=30679'. I downloaded both the x86 and x64 versions (although I only needed the x86 version for this project). They are executables that when run installs them. After installing them I found a copy of it in 'C:\Windows\SysWOW64' and in 'C:/Windows\System32'. And low and behold this problem was resolved.
What I learned from this process, was that it was difficult to know whether you have the right VC++ redistribution package installed or not. I thought I would have been installed when visual studio was installed with the VC++ features enabled. I'm using visual studio community version 2019. The project I am working with was a project I cloned from a GitHub source. I'm still confused about VC++ redistribution versioning. For example, could I have installed some later version and would it have worked (i.e. backward compatibility)?

I had the same issue. what worked for me is to add
<CefSharpBuildAction>Content</CefSharpBuildAction>
to the first PropertyGroup inside the csproj of the project you are dealing with.

I had the same issue even in release mode. Going through GitHub CefSharp FAQs, NOTE 2 solved my issue.
If compiling from source (not recommended, use the Nuget packages) and you notice that you can no longer build in debug mode, but release builds work just fine you may need to repair your version of Visual Studio. This happens in rare cases where you will get the same exact message as a missing unmanaged .dll file as shown above.
Had to repair Visual Studio and all started working as before.

For my future me, had this same issue and every time i get this error when i start my .net core 3.1 wpf application in visual studio -> Could not load file or assembly 'CefSharp.Core.Runtime.
That cost me hours!
My Solution: Don't initialize Cef in your WinForm or WPF Window class.
You need to initialize this in your startup main/app. In my example i need to add this:
public App()
{
CefSettings _browserSettings = new CefSettings();
...
Cef.Initialize(_browserSettings);
}

Visual Studio 2008 Setup Project does not include VC_redist

I know this must have been answered before, but I cannot find a reference...
Problem: How do I configure a Visual Studio setup project to include and install the VC redist package?
Info:
I am creating a Visual Studio 2008 C# Win Forms project that uses native code through a managed C++ dll. In order to install this program on users computers, I made a Visual Studio Setup project. The only problem is, I cannot seem to get the x86_redist package to be included in the install, thus, the program fails to launch on users computers who do not have VS. (Yes, this is a Release build.) I have attempted adding a PreRequisite in the C# program, and I have attempted adding a Merge Module in the setup program.
Thanks for the help!
More detail:
The exact error message is this: Exception caught! System.IO.FileLoadException: Could not load file or assembly "MyInterface, Version=1.0.5354.28734, ..." or one of its dependencies. The application has failed to start because the application configuration is incorrect. Reinstalling the application may fix the problem. (Exception from HRESULT: 0x800736B1)
That HRESULT is a COM Exception, and essentially seems to wave its hands and say "Something bad happened". Any hints?

C# Unable to load DLL (Module could not be found HRESULT: 0x8007007E)

error:Unable to load DLL 'x.dll': The specified module could not be found. (Exception from HRESULT: 0x8007007E)
OS: Windows 7
I have two stations, Visual Studio 2012, using .net 4.0; the other don't have VS installed
On the first station with VS2012 I have a C# solution with a C++ project imported.
I'm using:
[DllImport("x.dll", CallingConvention = CallingConvention.Cdecl)]
[return: MarshalAs(UnmanagedType.I4)]
On this station is working.
But when I moved on the other station (that don't have VS installed) it appear that error.
If I install VS, it's working.
What are some possible reasons for this problem to occur? Any ideas on what I could be missing or how I could debug this problem?

The most likely reason is that the machine which does not have Visual Studio installed is missing the C++ runtime that is needed by your unmanaged DLL. Install the appropriate C++ runtime from the downloadable redistributable.
Do make sure that your unmanaged DLL is linked against the release runtime and not the debug runtime. The latter cannot be redistributed.
You can debug unmanaged DLL dependency issues using tools like Dependency Walker, Process Monitor etc.

I had the same problem
Use Dependency Walker to check the missing dependencies
In my case, I was missing msvcp110d.dll and msvcr110d.dll
I copied these two files from my dev PC to test PC's C:\Windows\SysWOW64 PC and worked!
Also, you can add Visual Studio C++ 11.0 DebugCRT(x86) as a dependency in InstallShield to make it work

Unable to Import a Visual Studio made C++ DLL into a Visual Studio C# Project on Windows

I have been trying to monitor video memory for a highly performance intensive program.
So I used the NVIDIA CUDA libraries in a C++ Visual Studio Application to collect the data I need.
Unfortunately I need a package that can be used with Ruby, C# and the Software Testing tools my company has.
So I decided to compile a C++ DLL and import it into a C# Visual Studio Project for testing.
I was able to compile the DLL but importing it into my Visual C# Program has been an issue.
I right Click on References -> Add Reference. Then I click on the Browse tab and browse to the location of my DLL; "TestProgram.dll" and I click "OK"
Then I get the following Error message "A reference to C:.... could not be added. Please make sure that the file is accessible, and that it is a valid assembly or COM component."
What I have tried so far:
1. Importing the DLL from several different locations on my system.
2. Moving the DLL into my Solution Explorer and importing it
3. Using the "Invoke" method: [DllImport("PathToMyDll")]
4. Using the "Invoke" method with just my dll name.
5. Typing 'using' path to my DLL
6. Exporting the dll as a .lib file instead
What am I doing wrong? I thought that if I exported a DLL using Visual Studio 2010 then surely that same DLL could be Added into a Visual Studio 2010 project.

Well, is it a valid Assembly or COM component? Just because it's a C++ DLL doesn't mean it can be used with just a reference, in fact, most can't. It needs to be a managed DLL or a COM object. If it's none of those, then you have to invoke unmanaged code from a managed assembly. That means defining each function in a stub.
More info here: how to call a C++ dll exported function from c#
Be aware, you also have to deal with 64/32 bit issues, since if the DLL is compiled for 32 bit, you can't use it in a 64 bit application.

I found the solution to this problem. CUDA creates a Windows Console Application project. So the solution was to just use that instead of a DLL.
This worked well because Ruby, Test Complete and Visual C# can read the output from a basic .exe console program (with some work).
The compiled exe is simple. All I need to do is pass in an integer as an argument when I launch the program and the program will get the data I need from my NVIDIA card.
The challenge now will be finding a good way to interface with the .exe.

C# Dll Import failure: "The application has failed to start because its side-by-side configuration is incorrect"

I have a c# .net 4 app , using vs 2010.
Im trying to import a c++ dll (built on vs 2005).
[DllImport("Card.dll")]
I get the failure:
Unable to load DLL 'Card.dll': The application has failed to start because its side-by-side configuration is incorrect. Please see the application event log or use the command-line sxstrace.exe tool for more detail. (Exception from HRESULT: 0x800736B1)
using sxstrace.exe I get:
ERROR: Cannot resolve reference Microsoft.VC80.DebugMFC,processorArchitecture="x86"
I also found out that:
MFC80D.DLL and MSVCR80D.DLL are missing
Notice this is not DebugCRT, as this problem was caused by using a Debug compiled DLL instead of Release. I now use the Release compiled dll and the problem is DebugMFC.
I've tried anything I could find online. In order to save time I will introduce what I tried, so I won't get this advises again:
1- I have installed Microsoft Visual C++ 2010 Redistributable Package + SP1 + Security updates
2- I have installed Microsoft Visual C++ 2008 Redistributable Package
3 - I have installed Microsoft Visual C++ 2005 Redistributable Package
4 - I tried running this app as "Release" and not as "Debug"
5 - I tried to set entryPoint to the DllImport
Non helped. I still get the same error. I didn't see any other advise online instead of the one listed above.
Can anyone help me?

Because it says "Cannot resolve reference Microsoft.VC80.DebugCRT,processorArchitecture="x86", that means you are missing a dependency on the debug crt runtimes for VC 8.0. This means you need to build a release, NOT debug, version of card.dll. Microsoft doesn't ship a redistributable package for debug CRT runtimes. Those only comes with visual studio. Therefore build a release version of card.dll, and that should help your situation.

Do you have control over building Card.dll? If yes, have a look at how it is built. It must be built with proper version of VC++ (the one delivered with VS 2005) with manifest enabled. Then, installing the 2005 Redist. package must solve the problem. In case you cannot build Card.dll yourself, you will have to analyse the embedded manifest (if any) and contact the authors to remedy the problem cooperatively.

A static library by default links to the dynamic runtime.
If you re-build the dll in VS2005, change your Configuration Properties | C/C++ | Code Generation | Runtime Library setting to static runtime to avoid that problem.

You can use Dependency Walker to try to figure out what dependencies your dll pulls. If it says it wants *d.dll, then it looks like it is not a release version. Ask your colleague to check build configuration.
To use debug version you can try the following:
Go to the c:\Program Files\Microsoft Visual Studio 9.0\VC\redist\Debug_NonRedist\x86\ (this is for Visual Studio 2008, x86, adjust the path according to your system).
Copy the Microsoft.VC90.DebugCRT and Microsoft.VC90.DebugMFC directories to the directory with your executable.
Adjust the assembly version in the manifest files in the copied directories (the declaration looks like: <assemblyIdentity type="win32" name="Microsoft.VC90.DebugCRT" version="9.0.30729.6161" processorArchitecture="x86" publicKeyToken="1fc8b3b9a1e18e3b"></assemblyIdentity>, change the 9.0.30729.6161 according to what your dll needs.
Try to run the application.
The needed assembly version can be found in the output of sxstrace or in the in the *.intermediate.manifest file alongside the dll in its build directory. Sorry, I do not have Visual Studio 2005 and can not give the exact number.