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WPF Cefsharp instance/object reference in class not working

I am spending too much time trying to solve this issue: i am trying to create a Core, because the project is already confusing me and it is not that big. The Core is a Class outside the main Thread. On the main Thread i named the Browser, browser :
<cefSharp:ChromiumWebBrowser x:Name="browser" x:FieldModifier="public" />
In the class i call it like this:
public class Core : MainWindow
{
public void winstenVerlies()
{
var currentdirectory = "https://www.google.nl";
this.browser.Address = currentdirectory;
}
}
I have tried numerous ways, this is the way i like it but they all give me the same message:
"object reference is not set on an instance of an object."
Any help is appreciated.

Problem solved. i researched it for weeks now, from what i can see is the problem is the root, when i use this or the object/function name when calling it, it does not get passed the root of the class, instead of the root of the project. here is how you bypass it.
pass the object trough the class.
public void winstenVerlies(ChromiumWebBrowser b)
{
var currentdirectory = "https://www.google.nl";
b.Address = currentdirectory;
}
then call it like so.
Core Menu = new Core();
Menu.winstenVerlies(browser);
Now i try'd this befor, it gave me error messages the last time, i did not trace the source of the problems.
All i know is it working now, and i am happy.
Have a nice day.

System.TypeLoadException: Method 'get_xxx' does not have an implementation

There are a lot of questions floating around with this problem and i've worked through them ll with no joy.
I am receiving this error:
Method 'get_UserImageCDNUrl' in type 'App.Web.WebConfig' from assembly
'App.Web, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' does
not have an implementation.
Which is really strange because I am trying to run Api.Web which has no reference to App.Web, the only thing they have in common are references to other projects (Models.Domain and Models.DTO).
I have an interface:
IResourceCompiler in an assembly "Models.Domain"
I have an abstract class which implements this interface in the same assembly (Models.Domain) called WebConfigBase
In the "App.Web" and "Api.Web" projects they each have a class called WebConfig which inherit from WebConfigBase, therefore both WebConfig classes in App and Api are implementations of IResourceCompiler.
I tried to add a property
string UserImageCDNUrl {get;}
to IResourceCompiler and added the property to WebConfigBase
public string UserImageCDNUrl
{
get { return ""; }
}
so the property would be accessible to both Api and Web projects through their own WebConfig classes, and i get the exception above.
I have looked for hours to try and see why this happens with no joy.
I've cleared my Obj folders, cleaned, rebuilt, checked for any instances in GAC (there aren't any) and i'm still stuck on this.
Everything works fine until i try to add a new property to the interface (and base class)

OK, so bizarrely adding a reference to App.Web in Api.Web and removing it again has solved the issue.
I have no idea why, but it did.
I changed the version of App.Web to 1.0.0.1 and the error was still showing 1.0.0.0, which is what prompted me to do it.
I wish there was a more reasonable explanation but there isn't. Such an infuriating issue i'm just glad to be done with it.
Best of luck to anyone else who experiences this, my thought's are with you

For the records, in my case this was caused by two projects referencing different versions of the same package. At least fixing this solved the issue.

There can be many reasons for this, all the previous answers represent a case of this problem.
What I suggest doing is:
while your program is running open Resource Monitor -> CPU tab and in the search handles input box, search for the assembly that supposedly doesn't implement that method.
In the search results you'll see the path of your assembly, and most likely the path that you see isn't the one that you expect. Delete the assembly from this unexpected path so that the correct assembly gets loaded.

In many cases I become this error.
It seems like Cached assembly and I found them in UserProfile.
My solution is:
Save solution and close Visual Studio
Delete entire folder "c:\Users(user)\AppData\Local\Microsoft\VisualStudio\14.0\ProjectAssemblies\"
Start Visual Studio
Work...
Hope it helps.

I just remove the reference of current project (which is showing error) , and add again to other project in which project this was referenced build and it start working fine.
hope this help someone.

try this
public interface IResourceCompiler
{
string UserImageCDNUrl {get;}
}
public abstract class WebConfigBase : IResourceCompiler
{
public abstract string UserImageCDNUrl {get;}
}
public class WebConfig : WebConfigBase
{
public override string UserImageCDNUrl { return "whatever you want";}
}
or that way too:
public interface IResourceCompiler
{
string UserImageCDNUrl {get;}
}
public abstract class WebConfigBase : IResourceCompiler
{
public virtual string UserImageCDNUrl {get { return string.empty;}}
}
public class WebConfig : WebConfigBase
{
public override string UserImageCDNUrl { return "whatever you want";} // or return base.UserImageCDNUrl ;
}

I was seeing this problem in Visual Studio 2017.
Upgrading to visual studio 2019 solved the problem for me.

Table has no (public) columns only on real device

I have the simplest of apps that I thought I would try on my device before I got too engrossed. However, I am getting the strangest error message when I run it on my iPhone (as apposed to the the emulator on my macbook).
Table has no (public) columns .
I am using the SQLite.Net PCL and I have built it from git hub as I had some problems with it not having the platform dlls for IOS otherwise.
Relevant code.
In my models I have this:
public class Setting
{
[PrimaryKey, AutoIncrement]
public long Id { get; set; }
[Indexed]
public string Key { get; set; }
public string Value { get; set; }
}
The code that throws this error message is the simple:
using (SQLiteConnection db = GetCon ()) {
db.CreateTable<Setting> ();
}
but in my opinion the strangest thing is that this code works fine on the emulator but crashes the application on the iphone itself.
If anyone has some ideas that would be great.
EDIT:
This error is thrown on the SQLite.Net-PCL library on this file line 380 but only on the device and not on the emulator.

For others to whom this may concern, I found the answer to my problem. The issue was with the Type not having any properties (the type in question the simple model class). Knowing that to be rubbish I found the following links that gave more information which I will relate in this post in case the links go dead:
Type.GetProperties returning nothing
NOTE: Be careful with assembly linker
If you're building with linker enabled you may need to use the class
somewhere, so it will not be ripped off at compile time. Sometimes,
only instantiating the class in your code is not enough, the linker
may detect that the instance is never used and will remove it anyway.
http://developer.xamarin.com/guides/ios/advanced_topics/linker/
The linking process can be customized via the linker behavior
drop-down in Project Options. To access this double-click on the iOS
project and browse to iOS Build > Linker Options, as illustrated below
(see link for details)
I have for now left it to be unlinked, however, I will try before release to get the linker to ignore these classes. Thanks for all your help.

I found my problem was just a (not that subtle) programming error. I was working with the TypeInfo class and wanted to use the Sqlite Connection method:
CreateTable (Type type);
What I had in my hand was a TypeInfo instance which I needed to convert back to the System.Type. I accidentally without thinking used the GetType() method instead of AsType() method which is obvious when you think about it. The clue I got was in the exception message along with the OP message was does System.Runtime have public properties?
var type = table.TypeInfo.AsType();
// var type = table.TypeInfo.GetType(); *WRONG*
connection.CreateTable(type);

Is it possible to use Gephi compiled with IKVM in a website?

I'm currently trying to load and use the Gephi Toolkit from within a .Net 4 C# website.
I have a version of the toolkit jar file compiled against the IKVM virtual machine, which works as expected from a command line application using the following code:
var controller = (ProjectController)Lookup.getDefault().lookup(typeof(ProjectController));
controller.closeCurrentProject();
controller.newProject();
var project = controller.getCurrentProject();
var workspace = controller.getCurrentWorkspace();
The three instances are correctly instantiated in a form similar to org.gephi.project.impl.ProjectControllerImpl#8ddb93.
If however I run the exact same code, with the exact same using statements & references, the very first line loading the ProjectController instance returns null.
I have tried a couple of solutions
Firstly, I have tried ignoring the Lookup.getDefault().lookup(type) call, instead trying to create my own instances:
var controller = new ProjectControllerImpl();
controller.closeCurrentProject();
controller.newProject();
var project = controller.getCurrentProject();
var workspace = controller.getCurrentWorkspace();
This fails at the line controller.newProject();, I think because internally (using reflector) the same Lookup.getDefault().lookup(type) is used in a constructor, returns null and then throws an exception.
Secondly, from here: Lookup in Jython (and Gephi) I have tried to set the %CLASSPATH% to the location of both the toolkit JAR and DLL files.
Is there a reason why the Lookup.getDefault().lookup(type) would not work in a web environment? I'm not a Java developer, so I am a bit out of my depth with the Java side of this.
I would have thought it possible to create all of the instances myself, but haven't been able to find a way to do so.
I also cannot find a way of seeing why the ProjectController load returned null. No exception is thrown, and unless I'm being very dumb, there doesn't appear to be a method to see the result of the attempted load.
Update - Answer
Based on the answer from Jeroen Frijters, I resolved the issue like this:
public class Global : System.Web.HttpApplication
{
public Global()
{
var assembly = Assembly.LoadFrom(Path.Combine(root, "gephi-toolkit.dll"));
var acl = new AssemblyClassLoader(assembly);
java.lang.Thread.currentThread().setContextClassLoader(new MySystemClassLoader(acl));
}
}
internal class MySystemClassLoader : ClassLoader
{
public MySystemClassLoader(ClassLoader parent)
: base(new AppDomainAssemblyClassLoader(typeof(MySystemClassLoader).Assembly))
{ }
}
The code ikvm.runtime.Startup.addBootClassPathAssemby() didn't seem to work for me, but from the provided link, I was able to find a solution that seems to work in all instances.

This is a Java class loader issue. In a command line app your main executable functions as the system class loader and knows how to load assembly dependencies, but in a web process there is no main executable so that system class loader doesn't know how to load anything useful.
One of the solutions is to call ikvm.runtime.Startup.addBootClassPathAssemby() to add the relevant assemblies to the boot class loader.
For more on IKVM class loading issues see http://sourceforge.net/apps/mediawiki/ikvm/index.php?title=ClassLoader

How do I pass references as method parameters across AppDomains?

I have been trying to get the following code to work(everything is defined in the same assembly) :
namespace SomeApp{
public class A : MarshalByRefObject
{
public byte[] GetSomeData() { // }
}
public class B : MarshalByRefObject
{
private A remoteObj;
public void SetA(A remoteObj)
{
this.remoteObj = remoteObj;
}
}
public class C
{
A someA = new A();
public void Init()
{
AppDomain domain = AppDomain.CreateDomain("ChildDomain");
string currentAssemblyPath = Assembly.GetExecutingAssembly().Location;
B remoteB = domain.domain.CreateInstanceFromAndUnwrap(currentAssemblyPath,"SomeApp.B") as B;
remoteB.SetA(someA); // this throws an ArgumentException "Object type cannot be converted to target type."
}
}
}
What I'm trying to do is pass a reference of an 'A' instance created in the first AppDomain to the child domain and have the child domain execute a method on the first domain. In some point on 'B' code I'm going to call 'remoteObj.GetSomeData()'. This has to be done because the 'byte[]' from 'GetSomeData' method must be 'calculated' on the first appdomain.
What should I do to avoid the exception, or what can I do to achieve the same result?

The actual root cause was your dll was getting loaded from different locations in the two different app domains. This causes .NET to think they are different assemblies which of course means the types are different (even though they have the same class name, namespace etc).
The reason Jeff's test failed when run through a unit test framework is because unit test frameworks generally create AppDomains with ShadowCopy set to "true". But your manually created AppDomain would default to ShadowCopy="false". This would cause the dlls to be loaded from different locations which leads to the nice "Object type cannot be converted to target type." error.
UPDATE: After further testing, it does seem to come down to the ApplicationBase being different between the two AppDomains. If they match, then the above scenario works. If they are different it doesn't (even though I've confirmed that the dll is loaded into both AppDomains from the same directory using windbg) Also, if I turn on ShadowCopy="true" in both of my AppDomains, then it fails with a different message: "System.InvalidCastException: Object must implement IConvertible".
UPDATE2: Further reading leads me to believe it is related to Load Contexts. When you use one of the "From" methods (Assembly.LoadFrom, or appDomain.CreateInstanceFromAndUnwrap), if the assembly is found in one of the normal load paths (the ApplicationBase or one of the probing paths) then is it loaded into the Default Load Context. If the assembly isn't found there, then it is loaded into the Load-From Context. So when both AppDomains have matching ApplicationBase's, then even though we use a "From" method, they are both loaded into their respective AppDomain's Default Load Context. But when the ApplicationBase's are different, then one AppDomain will have the assembly in its Default Load Context while the other has the assembly in it's Load-From Context.

I can duplicate the issue, and it seems to be related to TestDriven.net and/or xUnit.net. If I run C.Init() as a test method, I get the same error message. However, if I run C.Init() from a console application, I do not get the exception.
Are you seeing the same thing, running C.Init() from a unit test?
Edit: I'm also able to duplicate the issue using NUnit and TestDriven.net. I'm also able to duplicate the error using the NUnit runner instead of TestDriven.net. So the problem seems to be related to running this code through a testing framework, though I'm not sure why.

This is a comment to #RussellMcClure but as it is to complex for a comment I post this as an answer:
I am inside an ASP.NET application and turning off shadow-copy (which would also solve the problem) is not really an option, but I found the following solution:
AppDomainSetup adSetup = new AppDomainSetup();
if (AppDomain.CurrentDomain.SetupInformation.ShadowCopyFiles == "true")
{
var shadowCopyDir = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
if (shadowCopyDir.Contains("assembly"))
shadowCopyDir = shadowCopyDir.Substring(0, shadowCopyDir.LastIndexOf("assembly"));
var privatePaths = new List<string>();
foreach (var dll in Directory.GetFiles(AppDomain.CurrentDomain.SetupInformation.PrivateBinPath, "*.dll"))
{
var shadowPath = Directory.GetFiles(shadowCopyDir, Path.GetFileName(dll), SearchOption.AllDirectories).FirstOrDefault();
if (!String.IsNullOrWhiteSpace(shadowPath))
privatePaths.Add(Path.GetDirectoryName(shadowPath));
}
adSetup.ApplicationBase = shadowCopyDir;
adSetup.PrivateBinPath = String.Join(";", privatePaths);
}
else
{
adSetup.ApplicationBase = AppDomain.CurrentDomain.SetupInformation.ApplicationBase;
adSetup.PrivateBinPath = AppDomain.CurrentDomain.SetupInformation.PrivateBinPath;
}
This will use the shadow-copy directory of the main app-domain as the application-base and add all shadow-copied assemblies to the private path if shadow-copy is enabled.
If someone has a better way of doing this please tell me.