Namespace not recognized even though it is there

Question

I am getting this error      The type or namespace name  AutoMapper  could not be found  are you missing a using directive or an assembly reference     The funny thing is that I have that reference in my project already     And this is my code   using System Collections Generic  using DataContract  using SelectorDAL  using AutoMapper   namespace SpecimenSelect       public class SpecimenSelect   ISpecimenSelect               public SpecimenSelect                         SetupMaps                       private static void SetupMaps                         Mapper CreateMap lt SpecimenDetail  SpecimenDetailContract gt                 The other weird thing is that I have two other projects in my solution that both use AutoMapper and are referencing the exact same AutoMapper dll file   They both work perfectly fine   Here is a screen shot of one     and here is that code  that compiles fine    using System Collections Generic  using AutoMapper  using DataContract  using SelectorDAL   namespace PatientSelect        public class PatientSelect   IPatientSelect               public PatientSelect                         SetupMaps                       private void SetupMaps                         Mapper CreateMap lt Patient  PatientContract gt                 Mapper CreateMap lt OrderedTest  OrderedTestsContract gt                 Mapper CreateMap lt Gender  GenderContract gt                 Both references seem to have the same data on the properties page   What am I missing   I tried    Restarting Visual Studio Referencing without a using statement  ie AutoMapper Mapper CreateMap  Clean and Rebuild   Any other ideas

User · Answer

In my case I got the error only in VS 2015  When opening the project in VS 2017 the error was gone

User · Answer

This has to be the simplest solution if all the other answers does not help you  I was searching for what s wrong with my setup among the answers  Tried all of them - none worked  Then I realized Visual Studio 2018 was developed by Microsoft  So I did what most people do   Restarted Visual Studio And It worked

User · Answer

In my case  the referenced dll was build in higher version of  Net Framework  After I added the reference  I could use it  But as soon as I did a build  the  missing reference  error will pop up  I refresh the dll the error will go but it would never build  This post made me check the framework version and thus I could resolve it by building the referenced project in same version

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Acknowledging this as an older post but still figured I d add this suggestion to the list of responses since I hadn t seen it mentioned  If the unresolved reference exists within context of another Project in the Solution  Right-click the Project having the problem  select Build Dependencies -- gt  Project Dependencies and ensure the desired Project is selected for reference  I had the same issue as described in the post however none of the suggested manners for resolution worked  I d never seen such a quirk in VS before  running VS 2019 at present  I checked for potential namespace issues and a plethora of the more obvious causes and nothing made sense  Intellisense even acknowledged the existence of the other Project and suggested to a the using statement but even after having added the using reference  VS 2019 still wouldn t acknowledge the other project  Forcing the dependency in the manner described resolved the issue

User · Answer

If your class does not compile  even if it is in the project check these    whether class name is exactly the same whether name space is exactly the same whether class properties show build action   compile

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In my case removing adding that assembly worked

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This question has already been answered for the original poster  but in case someone encounters this in an MS-Test project    from within Visual Studio  click the Test menu -  Test Settings -  Default Processor Architecture and ensure that the architecture matches that of the other assembly that you re referencing  If the other assembly is x64 and your test settings are x86  you may experience the symptoms that the original poster had

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I ve had a similar issue  that took a bit to troubleshoot  so I thought to share it   The namespace that could not be resolved in my case was Company Project Common Models EF  I had added a file in a new Company Project BusinessLogic Common namespace   The majority of the files were having a   using Company Project    And then referencing the models as Common Models EF  All the files that also had a   using Company Project BusinessLogic    Were failing as VS could not determine which namespace to use   The solution has been to change the second namespace to Company Project BusinessLogic CommonServices

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Let me ask a stupid question  Could there be two automapper dll files  One with an AutoMapper namespace and one without  Confirm the paths in both projects   I also noticed that the order of the using commands is different  It shouldn t matter  but have you tried to shuffle them

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Check to make sure that your project isn t set up to use the  NET Framework 4 Client Profile   You can check change this by right-clicking your project  not the solution   select Properties -  Application -  Target framework   The target framework is a dropdown on that page    This is a problem in Visual Studio  I would even go so far as to call it a bug    AutoMapper requires assemblies that are excluded from the  NET Framework 4 Client Profile   Since your project is using that version of the framework it breaks   A similar error will propagate to the build process when the  NET Framework version for the project you are referencing is higher than the project making the reference  i e  A project targeting 4 5 that references a project targeting 4 5 1 will give you this same error   There needs to be a better error message when this happens because there is no rational explanation as to why it would not build as the error message tells you to reference an assembly you have clearly referenced

User · Answer

Perhaps the project s type table is in an incorrect state  I would try to remove add the reference and if that didn t work  create another project  import my code  and see if that works    I ran into this while using VS 2005  one would expect MS to have fixed that particular problem by now though

User · Answer

This happened to me in Visual Studio 2019   For me  I was trying to reference another project in my solution   Here are the steps I took in case it helps anyone else    Ensured the project I wanted to reference was listed under References Ensured both projects were using the correct version of  NET Framework  Built the project  clicked green  Start  arrow    I was confused because I was still getting the error after steps 1 and 2  but building the project seemed to resolve it

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I have a similar problem with references not being recognized in VS2010 and the answers herein were not able to correct it    The problem in my solution was related to the extension of the path where the project referenced was located  As I am working with SVN  I made a branch of a repository to do some testing and that branch increased two levels in path structure  so the path became too long to be usable in windows  This did not throw any error but did not recognize the namespace of the project reference  When I correct the location of the project to have a smaller path everything went fine

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I resolved this issue by right clicking on the folder containing the files and choosing Exclude From Project and then right clicking again and selecting Include In Project  you first have to enable Show All Files to make the excluded folder visible

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I was working on Xamarin project and as always  deleting obj folder and rebuilding solved my issue  the namespace my VS was not recognizing was a code in my own project BTW

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In my case i had copied a classlibrary  and not changed the  Assembly Name  in the project properties  so one DLL was overwriting the other

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Crazy  I know   Tried all options here  Restarting  cleaning  manually checking in generated DLLs  this is invaluable to understanding if it s actually yourself that messed up     I got it to work by setting the Verbosity of MSBuild to  Detailed  in Options

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I faced similar problem of namespace method not being found during execution although it was fine during compilation  and the reason for this appears to be that the assembly I was referencing was deployed to GAC and since then was changed  so when I referenced the assembly in Visual Studion it was using the most recent one  but during runtime the version fro GAC had been used

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Restarting Visual Studio 2019 - that did it

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The question has already been awarded  but there are additional details not yet described that need to be checked   I too was having this behavior  where project B was referenced in project A  but the namespace of project B was not recognized in project A   After some digging  I found my path was too long   By reducing the path of the projects  both A and B  the references became visible and available   I tested this theory by creating project C at a much lesser path depth   I referenced project C in project A   The references worked correctly as expected   I then removed project C from the solution  merely moved project C to a deep path  the same as project B  and added project C back to the solution  and tried to compile   I then had no visibility to project C objects any longer

[c#] Namespace not recognized (even though it is there)

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