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On a new Win8.1 reinstall, with all of my code restored from backup, I'm suddenly now getting a Visual Studio warning when I build the main project of my solution:
Found conflicts between different versions of the same dependent assembly that could not be resolved. These reference conflicts are listed in the build log when log verbosity is set to detailed.
I set the Output log level to Detailed and I found a few entries like this:
There was a conflict between "mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" and "mscorlib, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e, Retargetable=Yes". "mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" was chosen because it had a higher version.
Trouble is, I'm not referencing mscorlib anywhere in the solution—old or new. I have a couple of apps on my machine that require .NET 3.5, but I can't see how that could be related.
One difference: the old Win8.1 install on which this warning did NOT occur was a standalone machine; this time I'm domain-joined. I don't know whether that makes a difference (I can't see how), but I thought I ought to mention it at least.
Having different versions of a Nuget package on different projects may cause this problem as well. Make sure that all your packages have the same version:
(Within Visual Studio) Right click on the solution
Click on Manage Nuget packages for Solution
Click on the Consolidate tab
For every package in the Consolidate tab, update the package to the same version for every project.
I was able to fix this by issuing an update-package -reinstall command at the Package Manager Console.
BUT
Be careful, updating all the packages in your solution could cause other problems, make sure you can roll back to a good version if it goes wrong!
I have been able to fix this issue by deleting my ".suo" file of my solution and then re-opening the solution. I then rebuild the solution and the issue is gone.
The ".suo" file is within the ".vs" folder which is what I usually delete.
Good luck!
I solved this by setting my verbosity to Diagnostic as per this answer.
Once I did that and rebuilt my solution, the build log actually listed the specific packages that depend on the two different versions of mscorlib.
In my particular case, my project had references to version 2.0.20126.16343 of System.Net.Http. I opened up the NuGet Package Manager and updated this package to the latest version (4.3.4 at the time). The next time I built my solution, the warnings were gone.
Well my solution is a little bit simpler than all of the above. I simply added a reference to the two Assemblies throwing this error (System.Runtime.Serialization and mscorlib) and rebuilt the project. By doing this, I specified the 4.0.0.0 version and removed the ambiguity.
One of the two (mscorlib) couldn't be added via the GUI because of the "A reference to 'mscorlib' could not be added. This component is already automatically referenced by the build system." error.
I needed to open the .vbproj (.csproj) file and add a reference manually via:
<Reference Include="mscorlib" />
I've tried all the following, but none has resolved the issue.
the command "update-package -reinstall".
Update and package via Consolidate tab.
Removing the ".suo" file.
However, My issue was a different case, I guess the new version of Xamarin.Forms package has used a different version of mscorlib. so I've downgraded it and it works fine.
I suggest you try all above solutions and also try to find which package is conflicting.
Following Memet Olsen's advice using VS2017 community...almost identical:
Right click Solution in Solution Explorer.
Select 'Manage Nuget Packages for Solution'
Check the packages. If any of them have a blue up-arrow rather than a green tick use the 'update' button
I also have tried all of the proposed solution to no avail.
In my project, this warning message was caused by a dll reference having a dependency on a different .net framework than the one that is targeted by my project.
In order to find out which dll reference was causing the warning, I simply used .net reflector to explore each dll reference to find out which one was referring a different .net framework (mscorlib).
In order to fix the issue, the reference dll has to be updated to a version which targets the same .net framework as the project using it, if such a version exist.
Hope this helps.
Okay, so we have a rather large solution with about 8 different projects inside it. Each of these projects depend on various different 3rd party assemblies. This solution is in the trunk branch of source control. We also have about 5 different branches off of trunk.
What is the best way to manage these 3rd party assemblies? When you add a reference to an assembly and then click it and view the properties window I notice that it has a hard coded path to the assembly.
For example: All our branches are mapped to "C:\Code\". So trunk would be "C:\Code\Trunk" and a branch would be "C:\Code\somebranch".
If I create a folder in "C:\Code\Trunk" called "Assemblies" and then drop all our 3rd party assemblies in that folder, and then I add a reference to an assembly in there is that assembly reference relative? If I click the added assembly I see the grayed out path property says "C:\Code\Trunk\Assemblies\someassembly.dll".
What happens if I then branch off of trunk? Would "somebranch" still have a reference to "C:\Code\Trunk\Assemblies\someassembly.dll" or would it then reference "C:\Code\somebranch\Assemblies\someassembly.dll"?
Currently we actually have a branch in source control called "Assemblies" which is mapped, just like any other branch, to "C:\Code\". So all branches with projects referencing assemblies have references to "C:\Code\Assemblies\someassembly.dll" no matter which branch the project is in, the path would be the same.
Unfortunately this means that you have to get the latest version of the branch you are working in AND the assemblies branch in order to get the solution to build successfully.
To sum it all up:
How do you add a reference that is relative to the solution? (i.e. Add a reference to C:\Code\Trunk\Assemblies\someassembly.dll and have that path be relative to the project that added it, so that when creating a branch it references the branched assemblies folder and not trunk's assemblies folder. Or is this reference already relative?
What are other recommended strategies for managing 3rd party assemblies?
Now we have nuget you can use it for all supported oss packages and even create your own nuget packages for other 3rd party assemblies. It is worth mentioning openwrap as an alternative to nuget.
nuget stores packages at solution level
so each branch (and trunk) would keep a version of these.
I'd suggest this is preferable behaviour. You would want to keep your assemblies version separate if upgrading a 3rd party for example.
In the past I've used svn's externals command to build the specific version from the internally developed dependencies. There's no reason you couldn't stick those in a repository and use externals (or you scm's equivalent) to get the right version.
I've used build events to get the dlls into the right place too.
Yes use an assemblies folder off of the trunk. I like the name lib better then assemblies.
Yes the path is already relative. When you branch your projects will get the correct assemblies folder.
Depending on how many third party assemblies you are using you make also want to organize your assemblies folder so it is not one big mess of dlls.
We have a SolutionItems folder in our solution for the 3rd party references.
Every branch of the solution has it's own copy.
When we add a reference we use the 'Browse' tab in the add reference dialog and select the assembly relative to our current project.
The Project file contains this:
<Reference Include="SomeAssembly, Version=0.1.0.0, Culture=neutral, PublicKeyToken=8xxxxxxxxxxx, processorArchitecture=MSIL">
<SpecificVersion>False</SpecificVersion>
<HintPath>..\Solution Items\SomeAssembly.dll</HintPath>
</Reference>
I usually create a common project that all the others reference. Inside that common project, I create a folder called deps (for dependencies). Each of the other projects then references the copy of the DLL in the common project's deps folder.
I'm trying to compile my excel addin using C# 4.0, and started to get this problem when building my project in Visual Studio. It's important to tell you that I haven't had this problem before. What could cause this to happen?
When I had this problem I fixed it by turning off the 'Enable ClickOnce security settings'.
Menu: Project | 'Project name' Properties... | Security tab | 'Enable ClickOnce security settings' check box.
My guess is that you're not working with strongly named assemblies. I've had this error when two projects reference slightly different versions of the same assembly and a more dependent project references these projects. The resolution in my case was to remove the key and version information from the assembly name in the .csproj files (it didn't matter anyway), and then do a clean build.
Changes between the different assembly versions were compatible with the parts of the solution referring to them. If this is not the case with you, you might have to do some more work to resolve the issue.
NuGet
With NuGet it's easy to get into this situation if:
You install a package to one project in your solution.
A new version of that package is deployed to the package source.
You install it to another project in the same solution.
This results in two projects in your solution referencing different versions of that package's assemblies. If one of them references the other and is a ClickOnce app, you'll see this problem.
To fix this, issue the update-package [package name] command at the Nuget Package Manager Console to bring everything up to a level playing field, at which point the problem goes away.
You should manage NuGet packages at the solution level rather than at the project level unless there is a compelling reason not to. Solution level package management avoids the potential of multiple versions of dependencies. When using the management UI, if the Consolidated tab shows 1 or more packages have multiple versions, consider consolidating them to one.
See this answer.
Go to the publish page and click on "Application Files". From there you should see a list of your DLL's. Ensure that the ones that are giving you trouble have their Publish Status marked as "Include" rather than "Prerequisite".
I've had this problem. It happened because i had many projects pointing to the same assembly but from different versions. I solve it selecting the same version to all projects in my solution.
If you have changed your assembly version or copied a different version of the managed library stated in the error you may also have previously compiled files referencing the wrong version. A 'Rebuild All' (or deleting you 'bin and 'obj' folders as mentioned in an earlier comment) should fix this case.
If you tried all the other answers in this question and you:
Have multiple projects in your solution
Have a project (Project A) that references another project (Project B), whose project references a NuGet package.
In Project A, you used Intellisense/ReSharper to bring in the reference to the NuGet package referenced in Project B (this can happen when a method in Project B returns a type provided by the NuGet package and that method is used in Project A)
updated the NuGet package via NuGet Package Manager (or CLI).
...you may have separate versions of the NuGet packages DLL in your projects' References, as the reference created by Intellisense/ReSharper will be a "normal" reference, and not a NuGet reference as expected, so the NuGet update process won't find or update it!
To fix this, remove the reference in Project A, then use NuGet to install it, and make sure the NuGet packages in all projects are the same version. (as explain in this answer)
Life Pro Tip:
This issue can come up whenever ReSharper/Intellisense suggests to add a reference to your project. It can be much more deeply convoluted than the example above, with multiple interweaving projects and dependencies making it hard to track down. If the reference being suggested by ReSharper/Intellisense is actually from a NuGet package, use NuGet to install it.
you need to sign the assembly with a key. Go in the project properties under the tab signing:
Adding my solution for this issue for anyone it might help.
I had a ClickOnce solution throwing this error. The app referenced a common "Libs" folder and contained a project reference to a Foo.dll. While none of the projects in the solution referenced the static copy of the Foo.dll in the "Libs" folder, some of the references in that folder did (ie: my solution had refs to Libs\Bar.dll which referenced Foo.dll.) Since the CO app pulled all the dependencies from Libs as well as their dependencies, both copies were going into the project. This was generating the error above.
I fixed the problem by moving my Libs\Foo.dll static version into a subfolder, Libs\Fix\Foo.dll. This change made the ClickOnce app use only the project version of the DLL and the error disappeared.
Deleting the DLL (where the error is occurred) and re-building the solution fixed my problem. Thanks
When this happened to me with the WindowsAPICodePack after I updated it, I just rebuilt the solution.
Build-->Rebuild Solution
I encountered this problem after migrating an Excel Addin from packages.config to PackageReference. Seems to be related to this issue.
The following works as a crude workaround if you're not using ClickOnce (it will omit all the dependency information from the .manifest file):
Unload project, edit .csproj
Find the section looking like this:
<!-- Include additional build rules for an Office application add-in. -->
<Import Project="$(VSToolsPath)\OfficeTools\Microsoft.VisualStudio.Tools.Office.targets" Condition="'$(VSToolsPath)' != ''" />
Edit a renamed copy of the referenced .targets file (in my case, the file resolved to C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\MSBuild\Microsoft\VisualStudio\v15.0\OfficeTools\Microsoft.VisualStudio.Tools.Office.targets and I made a copy Microsoft.VisualStudio.Tools.Office_FIX.targets in the same folder - didn't check if it works from a different folder).
Find the GenerateApplicationManifest element and change its attribute Dependencies="#(DependenciesForGam)" to Dependencies="".
Change the section found in 2. to reference your edited .targets file instead.
This will have to be repeated whenever the version of the .targets file shipped with VS is updated (or you won't get the updates), but I'm hoping it will be fixed soon...
There were too many projects in my solution to go through and individually update so I fixed this by:
Right-clicking my solution and selecting 'Manage NuGet Packages for Solution...'
Going to the Updates tab
Finding the affected package and selecting Update
Clicked OK and this brought all instances of the package up to date
Unloading and reloading the problem project solved it for me.
I went to publish, application files, found the dll throwing the error changed it to 'Include' from 'Include (Auto)'. I can now publish.
Is your assembly properly signed?
To check this, press Alt+Enter on your project (or right click, then Properties). Go to "Signing". Verify that the check box "Sign the assembly" is checked and the strong name key file is selected and "Delay sign only" is unchecked.
Now Here is a different approach to the problem:
Right click on the project and select the 'Unload Project' option. You will notice you project becomes unavailable.
Right click on the unavailable project and select the 'Edit' option.
Scroll down to the ' < ItemGroup > ' tag that contains all the resource tags.
Now go to the reference that has been displayed on the error list, you will notice it it uses a single tag (i.e. < Reference Include="assemble_name_here, Version=0.0.0.0, Culture=neutral" / >).
Change that to look as follows:
.
<Reference Include="assemble_name_here, Version=1.0.0.0, Culture=neutral, processorArchitecture=MSIL" >
< Private > True < / Private >
< HintPath > path_here\assemble_name_here.dll < / HintPath >
< / Reference >
Save your changes, Right click on the unavailable project again and click on the 'Reload Project' option, then build.
This is caused when you change the version of the .dll that is referenced. You need to delete all items, or the .dll in the target build folder.
I got the similar compiler error. Once I add the dependent project of the dll file to the solution, issue resolved.
If your main project using some library projects and have reference to them, you can cause this problem if your project reference to a assembly dll file instead to library project when you change something in your library project (ex: rename a class).
You can check all references to your main project by view in Object Browser window (menu View->Object Browser). A reference to a dll file always has a version number. Ex: TestLib [1.0.0.0]
Solution: delete the current reference of your main project to the library project and add reference to that library project again.
After trying most of the solutions here, I finally just added a reference to the project from the click once project, this changed it to Include (Auto) from Include and it finally worked.
What helped me was I went onto Package Manager Solution and looked at the installed package which was causing the issue. I saw that several projects were referencing the same package but different versions. I aligned them based on my needs and it worked.
I had this in a solution w/ 6 projects.
One of my projects was referring to the named assembly as a file reference. The others were all pointing to the project reference.
I usually get a different error in these cases.
My solution was to delete the named assembly anywhere it was referenced and add it back.
Once I worked through the project, ths problem disappeared.
Before doing this, I tried cleaning the solution as well as making sure none of the projects were signed.
hope it helps someone...
If its a mismatch of a dependencies dependencies, go to the NuGet package manager at the solution level and check the Update and Consolidate tabs, harmonise it all.
I recently hit this problem. In my case, I have NuGet packages on different assemblies. What I had was different versions of the same NuGet packages associated with my own assemblies.
My solution was to use the NuGet package manager upon the Solution, as opposed to the individual projects. This enables a "consolidation" option, where you can upgrade your NuGet packages across as many projects as you want - so they all reference the same version of the assembly.
When I did the consolidations, the build failure disappeared.
I also bump into kind of problem, all I just had to do is delete the .dll (can be found in reference) that causing the error and add it again.
Works like a charm.
Try with update-package -reinstall -ignoredependencies
Just go to Publish -> Application File -> And change the effected dll publish status from prerequisite to include!
This worked for me!
In my case, I upgraded the project to .net 4.7.2 but still built in old visual studio version (2015).
When i built the project in VS 2019, the build failure disappeared.
I'm getting the following error:
error CS1704: An assembly with the same simple name
'Interop.xxx.dll, Version=1.0.0.0, Culture=neutral,
PublicKeyToken=null has already been imported. Try removing one of the
references or sign them to enable side-by-side.
Everything I've seen says that I am referencing two assemblies with the same name and I need to remove one of them. However, I've checked and I'm only referencing it once.
This also only happens when I'm using msbuild to build from the command line on my dev box. If I build through Visual Studio or do a clean build on our CI server I don't see this error.
I've tried completely removing all of my source and building from scratch to more closely resemble the build machine but no luck.
So it looks like I can't read today!
The project had a reference to the Interop and a COM reference that generated the "same" interop. So there were two and I just didn't search very well. I still don't understand why it worked in other places but this did fix it.
In the Error List window, the project that was triggering this error was listed in the Project column. I got around the error by doing the following:
I unloaded the listed project (right-click => Unload Project)
Opened the XML for edit (right-click the unloaded project => Edit {ProjectName.csproj}).
Searched for the offending .dll, and noticed it was listed multiple times in the XML
Removed the entire Reference tag related to the offending dll, and did so for every copy of the reference except the first one listed
The reason it was listed multiple times was because several referenced libraries used that dll. This shouldn't be a problem, in and of itself, so I'm not sure what caused this error to suddenly pop up for me. I'll update this answer if I figure that out.
In my case the duplicate entry was caused by a NuGet package reference and a direct file reference to the same assembly in the packages folder. I am not sure how the project got into this state, but unloading the project and searching the XML file for the offending assembly name resolved the issue for me.
Note that in my case this started happening after updating a NuGet package to a newer version with no other changes to the project, so this maybe caused by a bug in NuGet.
If this is a web project, are there any strong-named references to the other version there? Those won't show up as a project dependency, but will cause a run-time error like you describe. Hope that helps
I had this problem but in my case, I had an old copy placed in the current folder for the EXE loading my component, that was loaded together with the current one, that was loaded by hand from my projects folder. Deleting that old copy solved my problem.
I used Debug > Windows > Modules window to see which modules were loaded at that time and that solved my problem.
For others facing the same as me: if building via command line using property AssemblyName, it will overwrite all assemblies generated by all solution projects - in other words, you will end up with (N -1) assemblies named the same where N is the no. of projects - the startup one (which generally will generate an exe).
This happens because all build command line properties are global and overwrite any project-specific setting. See this and this.
From the msdn link mentioned above:
Global properties are properties that are set by using the
/property switch on the command line, or properties that are set by
the integrated development environment (IDE) before a project is
built. These global properties are applied to all projects that are
built by using this Engine.
In my specific case, where Jenkins is the CI tool, I ended up adding a windows batch command at the end to rename the .exe only to what I originally intended when passing the AssemblyName parameter.
For those developing UWP projects that have project references that include specifically the Microsoft.Windows.SDK.Contracts nuget package (or other dependencies that reference it), this is a common error when the version of the SDK contracts is targeting a different version of the runtime to how your project is configured.
For instance, when targeting Windows 10, version 1903:
Any dependencies or reference projects should target or at least support the same runtime version.
it is common thought process to update all NuGet packages when a new stable version is available, but this is not always a helpful practise on its own. Just because a new stable version of a package is available does not mean that you should or that you can easily use that version.
Even though this package for SDK contracts has a stable update, it is not compatible with my main project configuration, Nuget does not know this so it allows the update.
This package is specifically designed to provide windows dlls for project types that DO NOT have windows platform targeting support, it copies the same dlls that are included by the UWP targeting config. By installing later versions of the package the references from the satellite project will be included in the output along with those provided due to platform targeting, ultimately causing OPs error.
There are similar SDK and targeting packs for Windows IoT Device Runtimes, this information should help you identify and resolve those issues if you get stuck on this issue as my team often does :)
In my case, the issue was on wrong characters in the ProjectReference section of my csproj file.
Background
I have a project that references another library I maintain, which I publish as a NuGet package.
Whenever I make changes to my library, I usually reference the local dll in my project to test and make sure everything looks good before I publish the library as a NuGet package.
When testing, I just comment out the PackageReference line and uncomment the ProjectReference one so it references my local dll, like so:
<ProjectReference Include="..\..\my-class-library\MyClassLibrary.csproj" />
<!--<PackageReference="MyClassLibrary" Version="2.0.1"/>-->
Root cause
I had the slashes inverted, so I was using / rather than \ in the path, like so:
<ProjectReference Include="../../my-class-library/MyClassLibrary.csproj" />
Once corrected, the issue went away.
Try this instead: remove Interop.xx.dll from the reference section in Solution Explorer and Rebuild the project
In our case this error was shown when we had a duplicate reference inside the .csproj file (although I have no idea how this happened).
The difference to an already posted answer is that, in our case, one was a project reference and another one was direct binary reference to a dll.
Once we removed one of those, project correctly compiled.
I have got a Visual Studio Solution containing several projects and have set up the references between the projects as project references.
When a reference to an assembly is added, the references' properties contain a setting for
Specific Version = True|False
This property is missing for project references. How can it be set? I'd like my solution to load any available assembly (no matter what version) in the bin folder.
I've had a problem when a workflow instance (Workflow Foundation) was deserialized and the dependencies were updated meanwhile.
I think the problem is that what you are asking is not possible directly with a project reference, I think that always implicitly turns into an 'explicit version', because of the nature of the link.
The way you could do this (calling the currently referenced project A, and the referencing project B):
Have the project you want to reference in your solution, just like you do now with the project reference
Explicitly set the dependency chain so the 'referenced' project is built first
Build the referenced project A once first manually
Create an assembly reference in project B to the results from the build in project A
Set the assembly reference to 'Specific Version = false'
The build order (dependency) will guarantee that A is always built before B, and B will reference it from the binary output directory of A.
(altho, it's a little brittle and I would not recommend it since it's easy to get wrong results if the settings are not all right, or the sun aligns with the stars wrong, or some such)
I might be misunderstanding your question, but when you add a project reference, the project's assembly is always loaded into any project that references it when the project is built. Therefore, you'll always have the latest available assembly in the bin folder for that project. VS treats projects differently than other assemblies in that regard.
You can add references to project output dlls instead of projects. Then you will be able to set Specific Version setting.
I have found the solution to my problem. It's described pretty detailed here.
The problem is not a matter of wrong project references, but more a de/serializing of workflow instances question.
Thanks to everybody who tried to help.