Why can t I reference my class library

Question

I have a solution that contains a website and a class library in Visual Studio 2008    I then have another web site project outside of the solution that needs to reference the class library  I right click the Bin folder or Project and select Add Reference  then select my Class Library Project  it adds the 15 or so DLLs that the class library needs to the websites bin folder  but none of the  cs files recognize the using statements   using MyLibrary MyFolder    It says that it can t resolve it  and ReSharper just says it can be safely removed since it s not being used   ReSharper can recognize that it needs the reference and suggests that it  Reference MyLibrary and use MyFolder   I m not sure why it s suggesting I add a reference I already have  When I go with the suggestion  I get the error       Failed to reference module  Probably  reference will produce circular dependencies between projects     I ve tried going to the websites property pages and removing all the references and re-adding them  but it gives the same errors  Any ideas why this isn t working

User · Answer

Since they are both in the same solution  instead of adding a reference to the DLL  add a reference to the class library project itself  the Add Reference dialog will have a tab for this    Ahh  it s a different solution  Missed that  How about you try instead of adding a reference to the project addding a reference to the compiled DLL of your class library  The Add Reference dialog has a Browse tab which does this

User · Answer

Another possible fix that just worked for me   If you have Assembly A  which references Assembly B  both of which reference a non-project  external  assembly X  and Assembly B s code will not recognize that you have referenced X  then try the following steps in order    Drop reference to X from BOTH A and B Recreate reference to X in B Recreate reference to X in A   Apparently  VS will not recognize a reference to an external assembly in a project that is a dependency of another project that already references the external  By setting up the references again from the ground up  you overcome this  It s just very odd

User · Answer

Also  check that the new solution s projects run against a compatible framework to the project you re trying to include   I was trying to include a reference to a 4 0 project in a 3 5 project

User · Answer

I had a similar issue in VS 2010  when creating a test project for an MVC 2 application  The symptoms were identical   The message from ReSharper was somewhat misleading  For a moment I completely ignored ReSharper and did it the  manual VS way     I cleaned the solution   I manually added the reference to the MVC project   I manually added the using directives   ctrl-shift-b   At this stage I got a compilation error  I should have referenced the System Web Mvc assembly in my test project  sigh   Adding this reference causes the project to compile  The ReSharper issues remain  but the ReSharper test runner works    When I restart VS  the ReSharper errors are gone too  I m not sure if the restart is required - simply closing the  cs file might be enough   From now on  when I see the ReSharper message     Failed to reference module  Probably    reference will produce circular   dependencies between projects    I ll read      Failed to reference module  Probably    reference will produce circular   dependencies between projects    or you are missing some references to dependencies of the reference s dependencies

User · Answer

I faced this problem  and I solved it by closing visual studio  reopening visual studio  cleaning and rebuilding the solution  This worked for me

User · Answer

If you re referencing assemblies for projects that are in the same solution  add a Project reference  using the  Projects  tab  rather than browsing for the dll in the  bin Debug  or  bin Release  folder  using the  Browse  tab    See screen shot below   Only browse for the assembly dll file if it s considered an external assembly

User · Answer

I had this problem  It took me ages to figure out  I had people over my shoulder to help  We rebuilt  cleaned and restarted Visual studio and this didn t fix it  We removed and re-added the references     All to no avail     Until   The solution to my problem was that my class declaration was spelt incorrectly   Before you start judging me harshly  allow me to explain why it wasn t stupid  and also why this mistake could be made by even the most intelligent of programmers   Since the mistake was early on in the name  it wasn t appearing in the intellisense class listing when I began typing    e g    Class name  Message cs  Declaration   public class Massage         code here      At a glance and in a small font  Massage looks identical to Message   Typing M listed too many classes  so I typed e  which didn t appear in the mistyped version  which gave the impression that the class wasn t being picked up by the compiler

User · Answer

I had similar issue  What worked for me is that I had added wrong Class Library from visual studio  I added by using the search feature of visual studio   What I needed to do was Add New Project   Visual C    Class Library  And this newly added class library is the right one and can now be added as reference to any project

User · Answer

You may forget to add reference the class library which you needed to import    Right click the class library which you want to import in  which contains multiple imported class libraries   -- Add- Reference Select Projects- Solution- select the class library which you want to import from- OK

User · Answer

This sounds like a similar issue with ReSharper   http   www jetbrains net devnet thread 275827  According to one user in the thread forcing a build fixes the issue  CTRL Shift B  after the first build    Sounds like an issue with ReSharper specifically in their case   Have you tried building regardless of the warnings and possible false errors

User · Answer

If both projects are contained within the same solution  it will be more apropiate if you add the reference for the project you need  not its compiled dll

User · Answer

I had a similar problems where VS would sometimes build and sometimes not  After some searching and attempts I discovered that I had an ambiguous reference to a class with the same name in different libraries   FileManager    The project that would not build were my Unit Tests that reference all modules in my solution  Enforcing the reference to a specific module sorted things out for me   My point is  Rather than blaming ReSharper or VS  it may be a good idea to double check if there really isn t some kind of circular reference somehow  More than often  classes with the same names in different modules could cause confusion and is often a symptom of bad design  like in my case

User · Answer

I had stumbled upon a similar issue recently  I am working in Visual Studio 2015 with Resharper Ultimate 2016 1 2  I was trying to add a new class to my code base while trying to reference a class from another assembly but Resharper would throw an error for that package   With some help of a co-worker  I figured out that the referenced class existed in the global namespace and wasn t accessible from the new class since it was hidden by another entity of same name that existed in current namespace   Adding a  global    keyword before the required namespace helped me to reference the class I was actually looking for  More details on this can be found on the page listed below   https   msdn microsoft com en-us library c3ay4x3d aspx

User · Answer

I had a similar problem  will all my references being buggered up by Resharper - The solution which worked for me is to clear the Resharper Cache and then restarting VS  tools- options- resharper- options-  general-  click the clear caches button and restart VS

User · Answer

After confirming the same version of asp net was being used   I removed the project   cleaned the solution and re-added the project  this is what worked for me

User · Answer

Unfortunately the only thing that worked for me was completely deleting and recreating the class library project  after having temporarily copied the class files in it elsewhere  Only then would the ASP Net web project recognise the using statements that referred to the class library project  This was with Visual Studio 2010  not using ReSharper

User · Answer

I found how to fix this issue  for me at least   Why it worked  I m not sure  but it did   I just tried against a second website that was having the same problem and the following solution worked for that as well    I tried the normal cleaning of the projects and rebuilding  shutting down all my Visual Studio instances and restarting them  even tried restarting my computer     What actually worked was opening up the project in Visual Studio  closing all the open tabs  and then shutting it down   Before I had left the tabs open because I didn t think it mattered  and I hardly ever close the tabs I m using

User · Answer

If using TFS  performing a Get latest  recursive  doesn t always work  Instead  I force a get latest by clicking Source control    Get specific version then clicking both boxes  This tends to work     If it still doesn t work then deleting the suo file  usually found in the same place as the solution  forces visual studio to get all the files from the source  and subsequently rebuild the suo file    If that doesn t work then try closing all your open files and closing Visual studio  When you next open Visual studio it should be fixed  There is a resharper bug that is resolved this way

User · Answer

I deleted   csproj user   resharper file  of my project  then  close all tabs and reopen it  After that I was able to compile my project and there was no resharper warnings

User · Answer

One possibility is that the target  NET Framework version of the class library is higher than that of the project

[c#] Why can't I reference my class library?

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