System MissingMethodException Method not found

Question

What once was working in my asp net webforms app now throws this error      System MissingMethodException  Method not found   The DoThis method is on the same class and it should work   I have a generic handler as such   public class MyHandler  IHttpHandler       public void Processrequest HttpContext context                 throws error now System MissingMethodException  Method not found        this DoThis                public void DoThis

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I ve just had this issue and it turned out that it was because I was referencing a previous version of the DLL from my UI project  Therefore  when compiling it was happy  But when running it was using the previous version of the DLL    Check references on all other projects before assuming you need to rebuild clean redeploy your solutions

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I had a test project that references 2 other projects that each referenced different versions  in different locations  of the same dll   This confused the compiler

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In my case  my project was referencing Microsoft Net Compilers 2 10 0  When I switched it to Microsoft Net Compilers 2 7 0  the error went away  What a mysterious error with such a variety of causes

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Must be a reference bug from Microsoft   I cleaned  rebuild on all my libraries and still got the same problem and couldnt resolve this   All i did was close the Visual Studio Application and opened it again  That did the trick    Its very frustrating that such a simple issue can take that long to fix because you wouldnt think that it will be something like that

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I resolved this issue by installing the correct  NET Framework version on the server   The website was running under version 4 0 and the assembly it was calling to was compiled for 4 5   After installation of  NET Framework 4 5 and upgrading the website to 4 5  all works fine

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In my case spotify exe was using the same port which my web api project wanted to use on a development machine  The port number was 4381   I quit Spotify and everything worked well again

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I got this exception while testing out some code a coworker had written   Here is a summary of the exception info   Method not found    quot System Threading Tasks Task1 lt Microsoft EntityFrameworkCore ChangeTracking EntityEntry1 lt System Canon gt  gt  Microsoft EntityFrameworkCore DbSet 1 AddAsync    This was in Visual Studio 2019 in a class library targeting  NET Core 3 1   The fix was to use the Add method instead of AddAsync on the DbSet

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In my case it was a folder with olders DLLs of the same name that those wich were referenced in my  csproj file although the path was explicitly given they were somehow included therefore the several versions of the same DLLs were in conflict

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I had a similar scenario where I was getting this same exception being thrown   I had two projects in my web application solution  named  for sake of example  DAL and DAL CustSpec   The DAL project had a method named Method1  but DAL CustSpec did not   My main project had a reference to the DAL project and also a reference to another project named AnotherProj   My main project made a call to Method1   The AnotherProj project had a reference to the DAL CustSpec project  and not the DAL project   The Build configuration had both the DAL and DAL CustSpec projects configured to be built   After everything was built  my web application project had the AnotherProj and DAL assemblies in its Bin folder   However  when I ran the website  the Temporary ASP NET folder for the website had the DAL CustSpec assembly in its files and not the DAL assembly  for some reason   Of course  when I ran the part that called Method1  I received a  Method not found  error   What I had to do to fix this error was to change the reference in the AnotherProj project from DAL CustSpec to just DAL  deleted all the files in the Temporary ASP NET Files folder  and then reran the website   After that  everything started working   I also made sure that the DAL CustSpec project was not being built by unchecking it in the Build Configuration   I thought I would share this in case it helps someone else in the future

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It s also possible the problem is with a parameter or return type of the method that s reported missing  and the  missing  method per se is fine   That s what was happening in my case  and the misleading message made it take much longer to figure out the issue  It turns out the assembly for a parameter s type had an older version in the GAC  but the older version actually had a higher version number due to a change in version numbering schemes used  Removing that older higher version from the GAC fixed the problem

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If developing with your own NuGet server  make sure the assembly versions are all the same    assembly  AssemblyVersion  0 2 6     assembly  AssemblyFileVersion  0 2 6     assembly  AssemblyInformationalVersion  0 2 6

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I came across the same situation in my ASP NET website  I deleted the published files  restarted VS  cleaned and rebuild the project again  After the next publish  the error was gone

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I just ran into this on a  NET MVC project  The root cause was conflicting versions of NuGet packages   I had a solution with several projects   Each of the projects had some NuGet packages   In one project I had a version of the Enterprise Library Semantic Logging package  and in two other projects  that reference the first  I had older versions of the same package   It all compiles without error  but it gave a mysterious  Method not found  error when I tried to use the package   The fix was to remove the old NuGet packages from the two projects  so that it was only included in the one project that actually needed it    Also I did a clean rebuild of the whole solution

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I had this problem when the method required a parameter that I was not specifying

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I ve had the same thing happen when I had a number of MSBuild processes running in the background which had effectively crashed  they had references to old versions of code    I closed VS and killed all the MSBuild processes in process explorer and then recompiled

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Using Costura Fody 1 6  amp  2 0  After wasting a bunch of time looking into this same kind of error with all other potential solutions not working  I found that an older version of the DLL I was embedding was in the same directory I was running my newly compiled  exe from  Apparently it looks for a local file in the same directory first  then looks inward to its embedded library  Deleting the old DLL worked   To be clear  it wasn t that my reference was pointing to an old DLL  it was that a copy of an old DLL was in the directory I was testing my application from on a separate system from that which it was compiled on

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In my case it was a copy paste problem  I somehow ended up with a PRIVATE constructor for my mapping profile   using AutoMapper   namespace Your Namespace       public class MappingProfile   Profile               MappingProfile                         CreateMap lt Animal  AnimalDto gt                          take note of the missing  public  in front of the ctor   which compiled perfectly fine  but when AutoMapper tries to instantiate  the profile it can t  of course   find the constructor

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Ran into this error after updating a variety of Nuget packages  Check your Visual Studio Error List  or build output  for a warning similar to the following      Found conflicts between different versions of the same dependent   assembly  In Visual Studio  double-click this warning  or select it   and press Enter  to fix the conflicts  otherwise  add the following   binding redirects to the  runtime  node in the application   configuration file          Double-clicking this warning in Visual Studio automatically adjusted a variety of bindingRedirect package versions in my web config and resolved the error

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Wrong Nuget Package Version     I had a unit test project which was pulling in our companies internal EF Nuget data access package and that code pulled in an external package whose version was way behind the current version    The issue was that the Nuget settings for the package was set to the least version  and the older version won and was used during operations      Hence it silently got the wrong version for a common assembly used by both the package and the app      Solution   By Setting updating the package in Nuget to use and  get  the latest  fixed the issue

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For posterity  I ran into this with an azure function  using the azure durable function   durable tasks framework  It turns out I had an outdated version of the azure functions runtime installed locally  updating it fixed it

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I had this happen to me with a file referenced in the same assembly  not a separate dll   Once I excluded the file from the project and then included it again  everything worked fine

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also    try to  clean  your projects or solution and rebuild again

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In case the problem is caused by an old version of the assembly in the GAC  This can help  How to  Remove an Assembly from the Global Assembly Cache

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In my case  there was no code change at all and suddenly one of the servers started getting this and only this exception  all servers have the same code  but only one started having issues    System MissingMethodException  Method not found         Stack   Server stack trace      at System ServiceModel Channels ServiceChannelProxy InvokeService IMethodCallMessage methodCall  ProxyOperationRuntime operation     at System ServiceModel Channels ServiceChannelProxy Invoke IMessage message   Exception rethrown at  0       at System Runtime Remoting Proxies RealProxy HandleReturnMessage IMessage reqMsg  IMessage retMsg     at System Runtime Remoting Proxies RealProxy PrivateInvoke MessageData amp  msgData  Int32 type     at myAccountSearch AccountSearch searchtPhone searchtPhoneRequest request     at myAccountSearch AccountSearchClient myAccountSearch AccountSearch searchtPhone searchtPhoneRequest request     at myAccountSearch AccountSearchClient searchtPhone String ID  String HashID  searchtPhone Phone1     at WS MyValidation String AccountNumber  String PhoneNumber    The issue I believe was corrupted AppPool - we have automated AppPool recycling going on every day at 3 am and the issue started at 3 am and then ended on its own at 3 am the next day

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I solved this problem by making a shelveset with my changes and running TFS Power Tools  scorch  in my workspace  https   visualstudiogallery msdn microsoft com f017b10c-02b4-4d6d-9845-58a06545627f   Then I unshelved the changes and recompiled the project  This way you will cleanup any  hanging-parties  that may be around in your workspace and will startup with a fresh one  This requires  of course  that you are using TFS

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This happened to me using MVC4  and I decided after reading this thread to rename the object that was throwing the error   I did a clean and rebuild and noted that it was skipping two projects   When I rebuilt one of them  there was an error where I d started a function and not finished it   So VS was referencing a model that I had rewritten without asking me if I wanted to do that

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Restarting Visual Studio actually fixed it for me  I m thinking it was caused by old assembly files still in use  and performing a  Clean Build  or restarting VS should fix it

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I ran into this issue  and what it was for me was one project was using a List which was in Example Sensors namespace and and another type implemented the ISensorInfo interface  Class Type1SensorInfo  but this class was one layer deeper in the namespace at Example Sensors Type1  When trying to deserialize Type1SensorInfo into the list  it threw the exception  When I added using Example Sensors Type1 into the ISensorInfo interface  no more exception   namespace Example       public class ConfigFile               public ConfigFile                         Sensors   new List lt ISensorInfo lt Int32 gt  gt                       public List lt ISensorInfo lt Int32 gt  gt  Sensors   get  set                     using Example Sensors Type1     Added this to not throw the exception   using System   namespace Example Sensors       public interface ISensorInfo lt T gt                String SensorName   get             using Example Sensors   namespace Example Sensors Type1       public class Type1SensorInfo lt T gt    ISensorInfo lt T gt                public Type1SensorInfo

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Check your References    Be sure that you are consistently pointing to the same 3rd party libraries  don t just trust versions  look at the path  across your solutions projects     For example  If you use iTextSharp v 1 00 101 in one project and you NuGet or reference iTextSharp v1 00 102 somewhere else you will get these types of runtime errors that somehow trickle up into your code     I changed my reference to iTextSharp in all 3 projects to point to the same DLL and everything worked

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In my case  the MissingMethodException was for a method that was in the same file   However  I had just added a NuGet package that uses  Net Standard2 to my 4 7 1-targeting project  which caused a version conflict for System Net Http  4 7 1  version 4 0 0 0  the NuGet package using  NET Standard 2 wants 4 2 0 0   This seem to be known issues that should be better in 4 7 2  see note 2    I had used a binding redirect like this in all other my projects  because there were exceptions as soon as it tried to load the 4 2 0 0 which I didn t have      lt dependentAssembly gt       lt assemblyIdentity name  System Net Http  publicKeyToken  b03f5f7f11d50a3a  culture  neutral    gt       lt bindingRedirect oldVersion  0 0 0 0-4 2 0 0  newVersion  4 0 0 0    gt     lt  dependentAssembly gt    Except in this one project  where it seems it tries to load System Net Http only while calling a local function that uses a System Net Http HttpResponseMessage as it s parameter or return type  parameter during debugging  return type when I run the tests without the debugger  also a bit strange   And instead of showing a message that it could not load the 4 2 0 0 version of System Net Http  it returns this exception

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Just in case it helps anyone  although it s an old issue  my problem was a bit odd   I had this error while using Jenkins   Eventually found out that the system date was manually set to a future date  which caused dll to be compiled with that future date  When the date was set back to normal  MSBuild interpreted that the file was newer and didn t require recompile of the project

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This is a problem which can occur when there is an old version of a DLL still lingering somewhere around  Make sure that the latest assemblies are deployed and no duplicated older assemblies are hiding in certain folders  Your best bet would be to delete every built item  and rebuild redeploy the entire solution

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This may have been mentioned already  but for me the problem was that the project was referencing 2 nuget packages  and each of those nuget packages referenced a different version of another nuget package   So   Project -  Nuget A -  Nuget X 1 1  Project -  Nuget B -  Nuget X 1 2  Both versions of Nuget X had the same extension method that was being called from Project   When I updated both Nuget A  amp  B to versions that referenced the same version of Nuget X  the error went away

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Have you tried turning if off and on again  Jokes aside  restarting my computer was what actually did the trick for me and isn t mentioned in any of the other answers

[c#] System.MissingMethodException: Method not found?

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