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

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?

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.

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).

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

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

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).

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?

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.

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.

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.

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.

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.

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.

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.

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

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.

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

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.

I had the exact same problem.
I tried closing Visual Studio numerous times, I tried deleting and adding a new class library.Checked if I had the right version, if I had referenced it in the target project. Nothing worked.
Then I thought maybe, just maybe I cannot reference the library because it was empty... and that was it.
As soon as I added a class to it the problem was fixed. So if you have tried everything and you are close to losing your sanity. Just try adding something to the class library.

the solution for was just adding the access modifier
my class didnt have any access modifier then i just added public and it worked!
Contracts class library:
namespace Contracts
{
public interface ILoggerManager
{
void LogInfo(string message);
void LogWarn(string message);
void LogDebug(string message);
void LogError(string message);
}
}
Logger service class library:
using Contracts;
using NLog;
public class LoggerManager : ILoggerManager
{
private static NLog.ILogger logger = LogManager.GetCurrentClassLogger();
public LoggerManager()
{
}
}

I tried various solutions for this issue. An old WebForms application refused to acknowledge the existence of a library even though a reference existed.
Oddly, what worked was to add and reference the class library in Visual Studio 2022, safe the project, then reopen in an earlier version of Visual Studio.

My solution was simple, but I'll share it in case someone else has the same issue and finds this question by googling like I did.
It turns out that the most recent build of the supporting DLL was done in Debug mode, and my code was looking at the Release version of the DLL. I rebuilt the DLL in Release mode and all is working properly.

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.

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.

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)

Related

Intellisense showing identifier not found error when everything build successfully

I am working on a small project involving a wpf-based UI program when I come to a intellisense problem. It constantly complains that several identifiers (class/method/property) cannot be found, and most of those are from another assembly. Similar issue has been asked by many other users of visual studio:
WPF assembly reference missing - project still building
Type or namespace cannot be found, when reference does exist
Getting "type or namespace name could not be found" but everything seems ok?
If the promble only happens on types in referenced assemblies I might just overlook it. But now even some types in the same assembly are determined 'missing' by intellisense. Today I created a new custom Window in this wpf project, and visual studio auto generated code for further use as follows:
public partial class ReceiveTest : Window
{
public ReceiveTest()
{
InitializeComponent();
}
}
Then intellisense told me that identifier 'InitializeComponent' cannot be found, and every control this window owns cannot be found either. This is really upsetting since it makes intellisense completely useless. Normally these 'missing' identifiers are declared in FileName.g.i.cs and managed by visual studio itself, however it seem visual studio somehow failed to recognize it.
Now I have done everything I can including solutions given in above links but failed again and again. Could anyone explain this problem and show me a way to solve it? I would be very very grateful.
P.S. I am using visual studio 2017 and PowerTool addon
Upgrading Test project from 2010 to 2017
Following this up on a recent problem with a test project on VS2017 after upgrade from 2010. Tried everything to get rid of the squiggly red and they wouldn't go.
Problem was that 'namespace.zone.section' had 'namespace' not found when it was there and seen by intellisense etc (and in some cases 'zone' or 'section')
Deleted sou files
Deleted project files
Deleted the references
Reapplied all after clean, restart, restart
server and all the above.
Still problem persisted.
So I deleted the test project (imported form 2010) recreated the project in 2017, copied all the original test classes into new project, added back all the other projects (supporting the tests), added moq etc back in. Only took about 20 mins.
And ... compiled and worked.
Conclusion was that the original project file (test project) had something in it that didn't get upgraded and screwed it all up. Anyway it is all fine now.
I post this so you don't have to wast your time.

Weird: C# Type or Namespace name could not be found - Builds successfully

I have a weird error showing up in my project when it is open in the VS2012 IDE. Everywhere where I make use of another referenced project it suddenly says "Type or Namespace name could not be found". And by "says", I mean it has the text underlined in red with the error when I hover over it. The intellisense doesn't work for that code. BUT (and here's the weird part), the errors do not show up in the error console and the project builds and runs fine.
I can even debug and step through the code and it works perfectly fine. So at runtime the project is referenced fine but at design time the IDE can't find it. This worked for the past 2 weeks, and only then suddenly went a little bonkers. It's really annoying because I am rubbish at coding without intellisense!
Has anybody ever seen anything like this or have any suggestions?
I had this. I referenced assemblies whose "Target Framework" were set to ".Net Framework 4" in the "Application" secion of the projects properties. I changed this to ".Net Framework 4.5" not just in the referenced assembly's project but also the project I was building and it worked. Give this a try.
I have found this is a known problem with VS2012. Check to see how you are building, 64 bit or 32 bit. It won't work with 64 bit but it will with 32 bit. It will say things are missing and design will not work, however the program will run fine. I have heard the new VS update that hasn't been released yet will fix it.
Manually delete all the references to the libraries of the other projects and re-add. Intellisense rebuilds whatever it needs at that point and doing this has helped me in the past.
Another source of this problem is a solution with multiple projects containing code for the same namespace. The compiler can handle this. Intellisense won’t.
Related to a couple other answers here, I had a "Data" project using a "Data" namespace. Built fine, but just started recently showing errors from intellisense (even though it continued building fine.) (VS 2015.)
I fixed this by changing my "Data" project and namespace to "MyCompany.Data".
Oddly, the problem didn't seem to show up until recently, but making the change did fix it. Presumably there was a conflict in namespace with another project or reference, which can build fine, but intellisense can't handle.
You can change this in the Application tab of Project properties. You can also open up an EDMX diagram, right click, choose model browser, choose the second collapsable item in the model browser tab, hit properties, and there you'll find the Namespace option for generated Entity Framework entities and contexts. (Similiarly, if you modify an Entity Framework Model's namespace, you might also need to change the related connection to match [in Web.Config for ASP.Net and MVC.])
Make sure that there is no class with the name same as Project default namespace.
make sure that you don't reference .net framework 4.5 projects in .net 4 projects!
Examine your .proj files in a text editor and make sure the paths to your references are correct.
This can also happen if you set the Build Action to "None" on the referenced file and forget about it.
I had the same problem, where it would build and run fine, it just would always show that error and I couldn't use intellisense with the class.
I actually used the automatic method of creating the class in a new file to resolve the issue, then just copied the code over from the real class. I deleted the old file, renamed the new file, and now it works.

CS0436: Type conflicts with the imported type

I am including an instance of the same source files in multiple assemblies using the Add As Link option. I specifically need to include an instance of the same source within these assemblies because it is responsible for licence validation which must occur internally to the assembly. Performing licence calls across module boundaries could introduce a security risk.
Some of the projects in my solution that include the code depend on other modules that also include it, resulting in warning CS0436:
"The type [type] in [licence.cs full path] conflicts with the imported
type [LicenceClass] in [dependency project also including licence.cs].
Using the type defined in [licence.cs full path]".
I have tried declaring a class alias, but the definitions internal to licence.cs cause the same warning. In the alias, there must be a reference to the duplicated class name which causes the same warning.
I know it is bad practice to duplicate source between assemblies, but it is intentional in this case. I would rather keep a central instance that each assembly links to rather than a dedicated instance with renamed classes to avoid the warnings.
The workaround I have is simply to ignore the warning using a #pragma. Is there a more elegant solution?
It is worth noting that another way to get such warnings is by simply setting a project in visual studio to reference itself: References -> Solution -> etc etc (how I figured this gem out is left as an exercise to the reader ...)
Visual Studio will happily comply, only to throw a wall of warnings of the type described by OP during build, which is to be expected (upon reflection) since every single class etc is getting defined twice.
The only time conflicts occur is when two dependent classes include the same class. There are two workarounds:
Disable the warning in classes that cause CS0436:
#pragma warning disable 0436
Have a separate instance of the class, uniquely named in each client project (undesirable from a maintenance point of view).
EDIT: There is also a solution: do what Mark suggests below, and mark duplicate classes internal.
I had a web application I converted from ASP.NET 3.5 to 4.5 when I moved to VS2015. I started seeing this as a warning, but the solution would still compile. There were no circular references, and cleaning the solution and deleting the bin and obj folders didn't help.
It turns out that VS2015 wasn't happy with some of my classes in the App_Code folder. The classes in here had the same namespace as the rest of the web pages in the parent folder. Once I moved these classes out of the App_Code folder and to the top level of the web application, the warnings went away.
In .NET Core you can also disable the warning in project.json:
{
"buildOptions":
{
"nowarn":
[
"CS0436"
]
}
}
I had this error but not with 2 different classes!
Each new class where in conflict with itself, so obviously I had that CS0436 Error.
After some struggling found out that it was about Mirror Asset that I was using in my multiplayer Unity project. Mirror somehow was including every new class that I make (and inherit from NetworkBehavior).
My external editor was VSCode (visual studio code, solution might also apply to visual studio).
Solution
in
Edit / Preferences / External tools / "Generate .csproj files for:"
I started testing different settings, and this worked for me:
(Not sure if the exact settings work for all, but not having the right files in project, leads to this error. like my case.)
Click Regenerate project files and restart Unity and VSCode after applying these settings (or the setting that suits your project).
I've met such a case when removed some source files temporarily and restored them back later. It happens that IDE (Rider in my case) tries to restore the classes so when they were missing it just added the reference to the resulting exe. Evidently, when I restored the files, they look as duplicate.
The reference IDE inserted looks like this and it's enough to just remove it to fix:
<Reference Include="AppName, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null">
<HintPath>bin\x86\Debug\AppName.exe</HintPath>
</Reference>

Class Library Intellisense not showing up after adding the dll to the references

In C#, I made a ClassLibrary that has one Namespace and one Class.
I saved it and build it.
in other Projects, when i use it, I add it to my references by browsing to the .dll location.
But The Problem is that its name is not showing up in the Intellisense.
i.e when I: using ... my dll doesn't show ..
I'm Importing the library to a ConsoleApp.
both of the App and the library target Framework is .NET Framework 4.0
and I made their Assembly Version 4.0.0.0 so they're the exact same.
is there a setting or something that I'm missing ?
how can i make it pop up ?
I'm using VS2010 Professional
Thank you for your help
Maybe this be usefull, I was having a similar issue, I have a Web project, add the reference to a Class Library by selecting the project, but if I made a change on the class library, I can´t see that change on the intellisense of the Web Project, after try many things, I see that in the recently added reference, the value of the option "Local Copy" was set "True", then I change it to false and everething works!
I had a similar issue but in my case it was a property on the class. If you go to the file properties and look for a Build Action. Somehow mine was set to Content it had to be set to Compile.
I am using Visual Studio 2013. I hope this helps someone else.
Is the namespace for your assembly different than the namespace for your currently open project? I've had times when the current project and an assembly share the same namespace path the intellisense can mess up.
In general, Visual Studio is pretty good about intellisense generation, especially for C#. But sometimes there are some interesting conditions regarding ambiguities, and especially mixing project types where it just doesn't quite work.
Placing your content in the same namespace makes me wonder if you've actually fixed the problem (it may just be autocompleting the namespace in the currently loaded project rather than the assembly), but if it allows you to continue working, then go with it!
Right click on project on which you add reference of your dll/project select menu project dependancies and select/MarkCheckBox for reference project/dll. then it will work fine.
If the class library project had its name changed after creation, then intellisense may fail finding it due to directory issues, I believe.
I created my class with the generic "ClassLibrary1" or whatever, and then later changed the default namespace, class name, and project name inside of VS2017. I closed VS2017 and changed the directory name to match my default namespace, and then re-associated the project file in VS2017, and then re-added the reference in my main project file.
All seems to be fixed now.

the type or namespace name could not be found (Reference present)

After I build a few of my references, which are present in the project and accessible through intellisense before the build is performed.
Unfortunately none of my projects are set to target Client Profile, as answered in this thread.
The type or namespace name could not be found
This seems to be the most common cause, does anyone know what else other than this can cause the same issue?
Edit:
The Types that aren't found are all from the referenced DLLs. I have the correct using directives for these and they are present in the resource folder, however they become underlined red after a build (I did try cleaning to).
My initial thought was the framework (the project is on v3.5), but I checked all my resources working or otherwise all where on v2 bar a few (working ones) on v4 which I removed temporarily to make sure we're causing issues.
Unable to access the project from my current location but will post any requested specifics as soon as I can.
edit:
Resolved the issue by deleting all of the custom class libraries... found and rebuilt each of their projects then added the new DLLs back into the project. Stored libraries weren't very organised, so I probably have some confliction between old/new versions.
Have you read the warning in the error list? You might need to install nuget package used by the referenced projects
for me the error warning was
All projects referencing "project file" must install nuget package Microsoft.Bcl.Build.
Are the projects being built correctly ?
Sometimes, you need to manually generate them (right click on them, generate), before being able to run a full build.
I dont exactly know why, but this might be the way to go for you.
~A few simple things to try before getting into more complicated water...
Try clicking:
Build->Clean Solution
Build->Build Solution
If this doesn't work, check your using statements are all there and correct, check your references all still exist.
I had a similar issue today, and I thought I would mention it here in case it helps someone else out. In my case, I have a VB.net Class Library which is referenced by a C# class library. The solution would build fine, but in the IDE, as soon as I started editing a file in the C# project, I would get errors about not finding a reference to the VB.Net library. It turns out that the VB.Net class library had a reference to System.web (lowercase w). I'm not sure how that came about -- but the solution was to delete that reference and replace it with a reference to System.Web (uppercase W).
Make sure all the projects in your solution have the same "Target framework" value

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