How do I fix the Visual Studio compile error mismatch between processor architecture

Question

I m new to project configuration in Visual Studio 2010  but I ve done some research and still can t quite figure this issue out  I have a Visual Studio solution with a C   DLL referencing the C  DLL  The C  DLL references a few other DLLs  some within my project and some external  When I try to compile the C   DLL  I get this warning      warning MSB3270  There was a mismatch between the processor architecture of the project being build  MSIL  and the processor architecture of the reference   internal C  dll     x86     It tells me to go to Configuration Manager to align my architectures  The C  DLL is set up with platform target x86  If I try to change this to something else  like Any CPU  it complains because one of the external DLLs it depends on has platform target x86   When I look at Configuration Manager it shows the Platform for my C  DLL as x86 and for my C   project as Win32  This seems like the right setup  surely I don t want the project for my C   project to have platform set to x64  which is the only other option presented   What am I doing wrong here

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A good rule of thumb is  open DLLs  closed EXEs   that is    EXE targets the OS  by specifying x86 or x64  DLLs are left open  i e   AnyCPU  so they can be instantiated within a 32-bit or a 64-bit process    When you build an EXE as AnyCPU  all you re doing is deferring the decision on what process bitness to use to the OS  which will JIT the EXE to its liking  That is  an x64 OS will create a 64-bit process  an x86 OS will create an 32-bit process   Building DLLs as AnyCPU makes them compatible to either process   For more on the subtleties of assembly loading  see here  The executive summary reads something like    AnyCPU     loads as x64 or x86 assembly  depending on the invoking process x86     loads as x86 assembly  will not load from an x64 process x64     loads as x64 assembly  will not load from an x86 process

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I had the same problem with SQLite opening connection  and using the Nuget and installing the component used in project  SQLite  fixed it  try installing your component this way and check the result

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For C  projects  the target of x86 does what it sounds like   It says that this assembly only supports x86 architectures   Likewise for x64   Any CPU on the other hand says that I don t care which architecture  I support both   So  the next 2 questions are  1  what is the configuration of the executable that uses these dlls  and  2  what is the bitness of your OS Computer   The reason I ask is because if your executable is compiled to run in 64-bit  then it NEEDS all dependencies to be able to run in 64-bit mode as well   Your Any CPU assembly should be able to be loaded  but perhaps it is referencing some other dependency that is only capable of running in x86 configuration   Check all dependencies and dependencies-of-dependencies to make sure everything is either  Any CPU  or  x64  if you plan to run the executable in 64-bit mode   Otherwise  you ll have issues   In many ways  Visual Studio does not make compiling a mixture of Any CPU and various architecture dependent assemblies easy   It is doable  but it often requires that an assembly that would otherwise be  Any CPU  to have to be compiled separately for x86 and x64 because some dependency-of-a-dependency somewhere has two versions

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This is a very stubborn warning and while it is a valid warning there are some cases where it cannot be resolved due to use of 3rd party components and other reasons  I have a similar issue except that the warning is because my projects platform is AnyCPU and I m referencing an MS library built for AMD64  This is in Visual Studio 2010 by the way  and appears to be introduced by installing the VS2012 and  Net 4 5   Since I can t change the MS library I m referencing  and since I know that my target deployment environment will only ever be 64-bit  I can safely ignore this issue   What about the warning  Microsoft posted in response to a Connect report that one option is to disable that warning  You should only do this is you re very aware of your solution architecture and you fully understand your deployment target and know that it s not really an issue outside the development environment   You can edit your project file and add this property group and setting to disable the warning    lt PropertyGroup gt     lt ResolveAssemblyWarnOrErrorOnTargetArchitectureMismatch gt None lt  ResolveAssemblyWarnOrErrorOnTargetArchitectureMismatch gt   lt  PropertyGroup gt

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If your C  DLL has x86-based dependencies  then your DLL itself is going to have to be x86  I don t really see a way around that  VS complains about changing it to  for example  x64 because a 64-bit executable can t load 32-bit libraries    I m a little confused about the configuration of the C   project  The warning message that was provided for the build suggests that it was targeted for AnyCPU  because it reported the platform that it targeted was  MSIL   but you indicated that the configuration for the project was actually Win32  A native Win32 app shouldn t involve the MSIL - although it would likely need to have CLR support enabled if it is interacting with a C  library  So I think there are a few gaps on the information side   Could I respectfully ask you review and post a bit more detail of the exact configuration of the projects and how they are inter-related  Be glad to help further if possible

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I ve had a similar problem before  specifically when adding a test solution to an existing x64 solution  like SharePoint  In my case  it seems to have to do with the fact that certain project templates are added as certain platforms by default   Here s the solution that often works for me  set everything to the correct platform in the Configuration Manager  the active configuration drop-down  says Debug normally  is a good way to get to it  and project platform  in project properties   then build  then set everything back to AnyCPU  Sometimes I have to remove and re-add some dependencies  DLLs in each project s Properties  and sometimes the  Run tests in 32 bit or 64 bit process   double-click Local testsettings and go to Hosts  has to be changed   It seems to me that this is just setting something then setting it back  but there s probably more going on behind the scenes that I m not seeing  It s worked fairly consistently for me in the past though

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You may also get this warning for MS Fakes assemblies which isn t as easy to resolve since the f csproj is build on command   Luckily the Fakes xml allows you to add it in there

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The C  DLL is set up with platform target x86   Which is kind of the problem  a DLL doesn t actually get to choose what the bitness of the process will be   That s entirely determined by the EXE project  that s the first assembly that gets loaded so its Platform target setting is the one that counts and sets the bitness for the process   The DLLs have no choice  they need to be compatible with the process bitness   If they are not then you ll get a big Kaboom with a BadImageFormatException when your code tries to use them   So a good selection for the DLLs is AnyCPU so they work either way   That makes lots of sense for C  DLLs  they do work either way   But sure  not your C   CLI mixed mode DLL  it contains unmanaged code that can only work well when the process runs in 32-bit mode   You can get the build system to generate warnings about that   Which is exactly what you got   Just warnings  it still builds properly   Just punt the problem   Set the EXE project s Platform target to x86  it isn t going to work with any other setting   And just keep all the DLL projects at AnyCPU

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I was getting the same warning i did this    unload project edit project properties i e  csproj add the following tag    lt PropertyGroup gt       lt ResolveAssemblyWarnOrErrorOnTargetArchitectureMismatch gt          None      lt  ResolveAssemblyWarnOrErrorOnTargetArchitectureMismatch gt   lt  PropertyGroup gt   Reload the project

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I had similar problem it was caused by MS UNIT Test DLL  My WPF application was compiled as x86 but unit test DLL  referenced EXE file  as  Any CPU   I changed unit test DLL to be compiled for x86  same as EXE  and it was resovled

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Use https   docs microsoft com en-us visualstudio msbuild customize-your-build directorybuildprops-example    add a Directory Build props file to your solution folder paste this in it      lt Project gt    lt PropertyGroup gt      lt ResolveAssemblyWarnOrErrorOnTargetArchitectureMismatch gt None lt  ResolveAssemblyWarnOrErrorOnTargetArchitectureMismatch gt    lt  PropertyGroup gt   lt  Project gt

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For my project  I have a requirement to be able to build to both x86 and x64  The problem with this is that whenever you add references while using one  then it complains when you build the other   My solution is to manually edit the   csproj files so that lines like these    lt Reference Include  MyLibrary MyNamespace  Version 1 0 0 0  Culture neutral  processorArchitecture x86   gt    lt Reference Include  MyLibrary MyNamespace  Version 1 0 0 0  Culture neutral  processorArchitecture AMD64   gt    lt Reference Include  MyLibrary MyNamespace  Version 1 0 0 0  Culture neutral  processorArchitecture MSIL   gt    get changed to this    lt Reference Include  MyLibrary MyNamespace  Version 1 0 0 0  Culture neutral   gt

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I had this problem today and just looking the building configurations in Visual Studio wasn t helping because it showed Any CPU for both the project that wasn t building and the referenced project   I then looked in the csproj of the referenced project and found this    lt PropertyGroup Condition      Configuration    Platform       Release AnyCPU    gt   lt DebugType gt pdbonly lt  DebugType gt   lt Optimize gt true lt  Optimize gt   lt OutputPath gt bin Release  lt  OutputPath gt   lt DefineConstants gt TRACE lt  DefineConstants gt   lt ErrorReport gt prompt lt  ErrorReport gt   lt WarningLevel gt 4 lt  WarningLevel gt   lt PlatformTarget gt x64 lt  PlatformTarget gt      Somehow this PlatformTarget got added in the middle of a config change and the IDE didn t seem to see it   Removing this line from the referenced project solved my problem

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There should be a way to make a  NET EXE DLL AnyCPU  and any unmanaged DLLs it depends on compiled both with x86 and x64  both bundled perhaps with different filenames and then the  NET module dynamically loading the correct one based on its runtime processor architecture   That would make AnyCPU powerful   If the C   DLL only supports x86 or x64 then AnyCPU is of course pointless   But the bundling both idea I have yet to see implemented as the configuration manager does not even provide a means to build the same project twice with a different configuration platform for multiple bundling allowing AnyCPU or even other concepts like any configuration to be possible

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I had a very similar warning in my build   My projects were set to target  NET 4 5  on the build server the Windows 8 1 SDK  for  NET 4 5 1  was installed   After updating my projects to target  NET 4 5 1  wasn t a problem for me  was for a completely new application   I didn t receive the warning anymore

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Just want to post for those not finding the answers here solved their problem  When running your application  make sure the solution platform drop down is correctly set  mine was on x86 which in turn caused me this problem

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I got this warning in Visual Studio 2012 when compiling a SQL Server 2012 SP1 SSIS pipeline script task - until I installed SQL Server 2012 SP2

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This warning seems to have been introduced with the new Visual Studio 11 Beta and  NET 4 5  although I suppose it might have been possible before   First  it really is just a warning  It should not hurt anything if you are just dealing with x86 dependencies  Microsoft is just trying to warn you when you state that your project is compatible with  Any CPU  but you have a dependency on a project or  dll assembly that is either x86 or x64  Because you have an x86 dependency  technically your project is therefore not  Any CPU  compatible  To make the warning go away  you should actually change your project from  Any CPU  to  x86   This is very easy to do  here are the steps    Go to the Build Configuration Manager menu item  Find your project in the list  under Platform it will say  Any CPU  Select the  Any CPU  option from the drop down and then select  lt New   gt  From that dialog  select x86 from the  New Platform  drop down and make sure  Any CPU  is selected in the  Copy settings from  drop down  Hit OK You will want to select x86 for both the Debug and Release configurations    This will make the warning go away and also state that your assembly or project is now no longer  Any CPU  compatible but now x86 specific  This is also applicable if you are building a 64 bit project that has an x64 dependency  you would just select x64 instead   One other note  projects can be  Any CPU  compatible usually if they are pure  NET projects  This issue only comes up if you introduce a dependency  3rd party dll or your own C   managed project  that targets a specific processor architecture

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I solved this warning changing  Configuration Manager  to Release  Mixed Plataform

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In addition to David Sacks answer  you may also need to go to the Build tab of the Project Properties and set Platform Target to x86 for the project that is giving you these warnings  Though you might expect it to be  this setting does not seem to be perfectly synchronized with the setting in the configuration manager

[.net] How do I fix the Visual Studio compile error, "mismatch between processor architecture"?

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