WinForms in a 64-Bit world – our strategy going forward

Klaus Loeffelmann

As a part of a community that thrives on innovation and growth, WinForms developers are often pushing boundaries to create new possibilities. Our developers are also responsible for the maintenance of mission critical line of business software, often well over a decade in the making. We value your trust and your passion for creating excellent software solutions with our tools. As you may be aware, the transition from 32-bit to 64-bit in Visual Studio 2022 has resulted in some complexities. We are aware that these changes are causing some speed bumps along your development journey, and we want to clarify these issues by pointing out workarounds already available and our additional plans to address them.

Embracing 64-bit: A Change for the Better

The decision to switch to a 64-bit platform is far more than a simple upgrade. It’s a major improvement that helps Visual Studio work better in several ways. One of the biggest benefits is the ability to use more memory. In the 32-bit version, there were limits to how much memory Visual Studio could use, which often led to slower performance or even errors when working on large projects. The 64-bit version removes these limitations, allowing Visual Studio to handle larger projects with greater efficiency.

Screenshot of the task dialog showing Visual Studio using a greater than 32-Bit amount of memory.

But it’s not just about having access to more memory. The switch to 64-bit also enables Visual Studio to make better use of your computer’s processor, particularly of its multiple cores. Because a 64-bit application can process more data at once, it can use more cores simultaneously and effectively, which leads to faster operations. This is particularly noticeable when building your project. If your project is large, with many files and lots of code, the build operation can be considerably faster on 64-bit. This means less waiting around for builds to complete, which helps you get your work done quicker. But those are not the only advantages. Others are:

  • Compatibility with 64-bit libraries: There are numerous 64-bit libraries and components that simply couldn’t be used effectively with a 32-bit version of Visual Studio. The 64-bit version enables better utilization and integration of these resources.

  • Enhanced Security: 64-bit systems have some built-in security advantages over 32-bit ones, including a feature called Address Space Layout Randomization (ASLR) that makes it more difficult for malicious code to exploit the system.

  • Future-proofing: As technology continues to evolve, more and more applications and operating systems are transitioning towards 64-bit architectures. By moving to 64-bit now, Visual Studio is following the wave, ensuring compatibility with future technological advancements.

  • Larger Datasets: With 64-bit computing, you can work with significantly larger datasets that previously might have been impossible to handle due to memory restrictions. This is particularly advantageous at design-time in data-intensive fields like machine learning, big data analytics but also for tasks which involve the processing of schemas of large and complex databases for example for code generation.

Where does WinForms fit in?

These advantages are also true for the WinForms Designer. It is very common for WinForms application to reflect complex business cases. As a result, those applications often contain of hundreds of Forms and UserControls which themselves can grow really big and complex. All of this leads to a lot of code which needs to be generated as soon as a Form gets edited. One of the biggest beneficiaries of the 64-bit transition is therefore undoubtedly the WinForms Designer. The Designer leverages the ability to access more memory in the 64-bit architecture, greatly enhancing its performance and capacity to handle complex design tasks.

32-Bit legacy component challenges

All this said, we are fully aware that this advancement comes with certain challenges concerning components which are bound to a 32-Bit architecture and which are used in the context of the Windows Forms designer for projects targeting .NET Framework Versions up to 4.8.1.

The shift from 32-bit to 64-bit systems is not just about increasing power, but it involves fundamental architectural changes. These changes directly affect how we manage .NET Framework versions and .NET Core applications. For instance, it is not possible to host 32-bit exclusive components in a 64-bit process or .NET Core types in a .NET Framework process. However, this should not be seen as an approach that could have been avoided. Instead, it’s a necessary part of the natural progression and evolution in technology.

What are my options?

You have several avenues to consider, each with its own advantages:

  • Move to .NET 8+: The most forward-thinking option, though, would be to upgrade to .NET 8 or higher. The .NET 8+ environment is the future of (not only) WinForms Application development and provides the most robust support, especially when it comes to third-party control vendors. With .NET 8+, you’re not just keeping up with the times – you’re staying ahead, ensuring that your applications are ready for whatever the future brings.

  • Use AnyCPU: Firstly, for the design time, switch everything to build with ‘AnyCPU’. The ‘AnyCPU’ compile option in Visual Studio offers a versatile solution for addressing the 32-bit component issue in your WinForms project. When your project is set to ‘AnyCPU’, Visual Studio will compile your application in such a way that it can run on both 32-bit and 64-bit platforms. In the context of design time, this flexibility means your process can run as 64-bit on a 64-bit system, allowing you to take full advantage of the benefits of 64-bit Visual Studio, such as improved memory utilization and faster operations. In many cases, this work quite well for projects, which require 32-Bit-runtime components. When it comes to runtime after a design session has finished, the ‘Prefer 32-bit’ project setting becomes key for compatibility with older 32-bit components or libraries. By enabling this setting, you’re instructing the Common Language Runtime (CLR) to run your ‘AnyCPU’ compiled application in a 32-bit process, even on a 64-bit system. This provides an environment where your 32-bit components function as expected, thereby maintaining the smooth operation of your application. While this approach does impose some of the 32-bit limitations, such as a smaller memory space, it offers an effective solution for balancing between the need for 64-bit design time capabilities and the requirements of 32-bit components at runtime.

  • Modernizing the 32-Bit components: If the first option is not feasible due to the architecture of the 32-bit component, you might consider migrating away from the 32-bit components. While this may require an initial investment of time and resources, the benefits you stand to gain in the long run are significant. Transitioning to a 64-bit environment offers not only better performance but also enhanced security. Moreover, it prepares your applications for future updates and advancements, thus ensuring their longevity.

If all those options are not working for your special case, then there is the out-of-process WinForms Designer as a final option:

Adapting to the New Landscape: The Out-of-Process Designers

To support .NET Core 3.1 and above, we’ve created an out-of-process version of the WinForms Designer; a separate process that can handle tasks that Visual Studio cannot execute as a .NET Framework process. This essentially required us to create an entirely new architecture and extensibility model to handle the two types of processes simultaneously. Upgrading to .NET does have its challenges with changes in both the runtime and in the new out-of-process designer. While we do have parity with the most important design time functions, there are cases where legacy approaches don’t really make sense to pursue any longer in the new technical landscape.

The out-of-process designer allows us to circumvent the restrictions that problematic with the in-process design, namely the issues of hosting components which are incompatible with the Target Framework of the hosting Designer, e.g., Visual Studio. This is accomplished by launching a new designer process, which then operates in the exact Target Framework Version, the WinForms project was set up to target, allowing for greater flexibility in managing components of different architectures.

In addition, the out-of-process designer permits us to provide support for higher versions of .NET, such as .NET 8, 9, and beyond. It does this by allowing components to utilize features from these newer versions of .NET that may not be compatible with the .NET Framework.

However, this also means that all the individual components and their control designers must be adjusted to work across different process boundaries. When you are using your own WinForms control libraries with highly customized design-time support through dedicated Control Designers which provide custom CodeDOM serialization, specialized type editors, customized adorner rendering or individualized Designer action items, you need to migrate your Designer code to use the WinForms Designer SDK. We’ve made strides towards this with our stock controls for .NET (Core, 5+). And what’s also important: Most of our bigger third-party Control Library partners also provide their product to be used for .NET Versions 5, 6 and 7 – and modernized versions for .NET 8 are in the making.

It’s important to note that as we’re addressing these issues, we’re prioritizing components based on usage. Some of the lesser-used components in .NET Core have had their designer support deprecated in favor of more commonly used components.

The Out-Of-Process Designer for .NET Framework Application with 32-bit Components

We saw that more people needed support with designing WinForms applications for the 32-Bit .NET Framework, since these applications used parts that only worked in a 32-bit process. That was the reason, we adapted the approach of the WinForms out-of-process-designer for .NET and are introducing the 32-Bit out-of-process .NET Framework designer based of this.

The out-of-process designer is engineered to spawn a separate 32-bit process that can host the components required for such applications. By doing so, it sidesteps the incompatibility between the 64-bit environment of Visual Studio and the 32-bit components. This design allows for smoother integration and compatibility, despite the disparity in system architectures.

If you try top open a WinForms .NET Framework project, which has a reference to a 32-Bit-Component, Visual Studio will automatically bring up a dialog and ask, if you want to open your project with the 32-Bit .NET Framework out-of-process designer.

Screenshot of a Dialog, which shows up on opening a WinForms Project with 32-Bit component references

Just like its counterpart for .NET, the out-of-process designer for 32-Bit .NET Framework WinForms applications aims to provide the same design time experience, preserving the ability to use existing, even legacy, 32-bit components. Despite the challenging task of bridging the architectural gap, we are committed to ensuring a smooth transition and maintaining the functionality you’ve come to rely upon, while also providing a pathway towards future upgrades and enhancements.

We understand that important legacy projects can rely on 32-bit ActiveX controls and other legacy components that are currently incompatible with Visual Studio 2022, specifically for projects which are not targeting .NET (Core, 5+) but .NET Framework up to Version 4.8.1. In these cases, the out-of-process designers can be the solution for many use cases. But note, that also the .NET (6+) WinForms out-of-process designer should be considered the preferred and best-practice way forward – you would get the best of both worlds: 32-Bit compatibility at design time and runtime and the latest, most modern and most performant .NET version.

It is important to note that the updated out-of-process 32-Bit .NET Framework designer will not achieve full parity with the old in-process .NET Framework Designer due to the same architectural differences mentioned for the out-of-process designer for .NET Core. That also means that highly customized Control Designers will not be compatible to the .NET Framework in-process designer out of the box. If you use custom control libraries from 3rd parties you need to check if they offer versions which support the out-of-process .NET Framework Designer.

Supporting Legacy Components: Our Commitment and Plans

The out-of-process designers are where we are putting in most of our efforts going forward. And here is the planning of our road map for this current year:

  • Improving the 32-Bit Framework out-of-process designer: This designer will be the choice for maintaining projects, which cannot be migrated to .NET (Core, 5+), but depend on legacy 32-Bit components. This designer will not have feature parity with the in-process designer, but we will be adding more features as we see the customer demand for it. Note that the 32-Bit-Framework Designer is in Preview already and can be activated through the Tools/Option page.

For the Visual Studio 2022 version 17.9 we released a feature which assists you to easily choose whether a .NET Framework project should be opened for the classic Visual Studio-in-process designer or the out-of-process designers. The differences compared to the classic WinForms in-process-designer will be:

  • You will be able to open and design Forms and UserControls which are targeting .NET Framework (up to version 4.8.1) and rely on 32-bit-based ActiveX components or most other reasons, which would force the resulting assembly to be 32-Bit in the Designer.

  • If you are depending on special 3rd party control libraries for projects which rely on legacy 32-bit components, you cannot use the same versions of those libraries which the 3rd party vendors provide for the classic in-process designer. Check with your control library vendor, if they provide an updated version for the .NET Framework out-of-process designer.

  • The typed DataSet designer and SQL Server query editor in the context of designed DataSets will only remain available for the classic in-process designer. We will, however, introduce updated features later this year, which make it easier and possible to consume Data Sources based on existing Typed DataSets, so that maintaining Data Binding scenarios based on existing data sources will continue to be supported. We have no plans, however, at this time to support the classic Data Source tool windows in the .NET Framework out-of-process designer.

  • Data Sources based on classic SOAP Web services will not be supported by the out-of-process designer for either .NET or .NET Framework applications.

  • Providing the infrastructure for Root Designers: Third party vendors and control library authors rely on Root Designers – for example when they want to migrate their report designers from .NET Framework to .NET Core. By adding root designer support to the out-of-process designer, we’ll enable control authors to modernize their powerful reporting designers and other document designer types and bring them to .NET 6, 7 and 8+. We have, however, no plans at this time, to support custom Root Designers for the .NET Framework out-of-process Designer.

Moving Forward: A Collaborative Effort

The transition to a 64-bit system is a significant milestone that requires a new approach, innovative solutions, and patience. As mentioned before, this is not a quick bug fix; rather, it’s a transition that we need to manage together as a community.

We are committed to making this journey as smooth as possible for you. Your feedback is invaluable, and it helps us identify the areas where we need to focus our efforts. We have a road map and we’re making progress, but the timeline for completion depends on the unique challenges that you bring to our attention.

In conclusion, we understand the complexities you’re facing, and we want to reassure you that we’re making strides in addressing these challenges. Remember, change often comes with a bit of discomfort, but it paves the way for growth and better outcomes. We want to underscore the importance of your active engagement in this ongoing transition. As we continually strive to improve and fine-tune the 64-bit designer and our out-of-process designer support, your feedback and error reports are invaluable. If you encounter any specific issues while using WinForms, we strongly encourage you to report them directly in the WinForms repository on GitHub or via the feedback feature of Visual Studio. Detailed, concrete issue reports, especially those that include information about the environment, steps to reproduce, and the specific error messages, help us immensely in identifying and addressing problems more effectively and rapidly. Your participation in this process is crucial for the successful development of a more robust and efficient Visual Studio, since the technology, legacy 32-Bit-components are based all, is in many cases 20 years old and older.

Final Thoughts

The journey from 32-bit to 64-bit has been a complex one and not without its challenges. We’re committed to making this transition as smooth as possible for all our users, but we understand that there will be bumps along the way.

Thank you for your support and commitment as we push forward to a more capable and versatile WinForms ecosystem, and as always…

…happy coding!


Discussion is closed. Login to edit/delete existing comments.

  • Dmitry Grabarev 2

    Moving to .NET 8+ sounds great but in most cases, it is a challenge since this framework is not part of Windows distribution.

    • Juri Ryazanov 2

      Nothing stops you from building self contained app that doesn’t depend on whatever .NET runtime is installed or not installed at all on target machine…

      • Gauthier M. 4

        …which will produce a 200MB binary…

        • Jim Foye 2

          Ditto for WPF. It’s weird how nobody seems to care about this problem.

          • Artjom Melnikov 2

            Why would anyone care? Have you looked at your desktop apps: Discord, Github Desktop, NXZT CAM etc etc they all are more than 200mb. I also produce single assembly for WPF that is about 210mb and it doesn’t bother anyone.

          • Tyler 2

            Because it isn’t a problem.

        • Juri Ryazanov 3

          200 MB is nothing these days…

          Not to mention that you can always create an installer for your app that installs all required dependencies…

          • Klaus LoeffelmannMicrosoft employee 7

            There are scenarios, where 200 MBytes is definitely a challenge, not only because of size in lower-bandwidth deployment/update scenarios, also when it comes to start-up times. That’s the reason (disclaimer: no promises, no date at this point 🙂 ), we’re actively looking into what options we have for trimming and AOT’ing WinForms apps.

          • Kris Golko 1

            It would have been useful if it was possible to customise the message about missing run-time. If users don’t have admin access to install it, there’s no point in showing the download prompt. There should be an easy way to display company-specific instructions on how to request the run time.

      • Stefan Gentzmer 0

        Including all security issues of the framework in your self contained app.

      • Peter Kneale 0

        Actually theres one thing, building a self contained app triggers the anti-virus on my corporate laptop. Regular dotnet development is fine in every other respect but every time I make a self-contained app the AV immediately quarantines the executable.

    • Michael Taylor 1

      This is no different than the “challenge” that C++ programmers have had for decades. In order to run my app I need the version of the C++ RTL that I built against. The solution is that your installer has to ensure the necessary runtime components are installed. Every installer already supports this so it isn’t an issue in most cases.

      I really think having .NET Framework installed as part of the OS for so long has just spoiled people on having to deal with dependencies. Even with NF you had this challenge since you might require NF 4.8 and the OS might have shipped with NF 4.7.2.

      I see no challenge here.

  • Rodrigo Luna 0

    Two issues (at least).

    First, please find a way to implement themes out of the box.

    Two, what about the underlying API where freaks of the past like LVIS_OVERLAYMASK live and DllImports, P/Invokes, etc are now used?

    • Klaus LoeffelmannMicrosoft employee 1

      First, please find a way to implement themes out of the box.

      We’re definitely considering this. At the same time, WinForms is a wrapper around Win32, so, we’re also a bit dependent on with what we can work with in terms of dark mode, and we also always need to keep accessibility as a top priority. But, yes, definitely on our radar!

      Two, what about the underlying API where freaks of the past like LVIS_OVERLAYMASK…

      Not sure exactly what your ask is here. Can you clarify what you mean?

  • Jan Seris 0

    talking about 64bit, how is it possible to run a WinForms .NET 8 app as 64bit?
    When default “Any CPU” compilation is set, the process runs out of memory after 3 GB.
    The use case is testing processing many GB of files (in memory) via WinForms UI using .NET 8 backend library.

    • Klaus LoeffelmannMicrosoft employee 1

      Can you check via the Windows TaskManager on the Tab Details, if that app is indeed running as a 64-Bit app (column Architecture)?

    • Yousof Zaatari 1

      You must have prefer 32-bit checked in your project properties window.

    • John Tur 1

      There is no such thing as “Any CPU” EXE projects in .NET 8, the application will run as 64-bit automatically unless you specifically compile it as 32-bit

  • Péter Ádám 1

    “The typed DataSet designer and SQL Server query editor in the context of designed DataSets will only remain available for the classic in-process designer.” – poof, yet another distinctive feature fell prey for the dumbing down to Mac.

    “Data Sources based on classic SOAP Web services will not be supported by the out-of-process designer for either .NET or .NET Framework applications.” – poof, yet another distinctive feature fell prey for the dumbing down to Mac.

    After merging the Win98/Me line with Win2000 into WinXP, I never expected that once MS will merge VS into VS Code…

    • Jorge Morales Vidal 0

      What are you talking about?

  • uzochukwu Godwin 0

    Hello, I am creating a WinForm application using .NET 8.0. When I am done building the form using the drag-and-drop option, It throws an error when I try to debug it. Please, can anyone help point me to what exactly could be the problem?

    Here is the error message that I received:

    Severity Code Description Project File Line Suppression State Details
    Error CS1061 ‘CreateTournamentForm’ does not contain a definition for ‘teamOneScoreLabel_Click’ and no accessible extension method ‘teamOneScoreLabel_Click’ accepting a first argument of type ‘CreateTournamentForm’ could be found (are you missing a using directive or an assembly reference?) TrackerUI C:\cs11dotnet7\TournamentTracker\TrackerUI\CreateTournamentForm.Designer.cs 80 Active

  • Nicolas MUSSET 0

    In the 32-bit version, there were limits to how much memory Visual Studio could use, which often led to slower performance or even errors when working on large projects. The 64-bit version removes these limitations, allowing Visual Studio to handle larger projects with greater efficiency.

    That’s nice and all. But it would be better to also have a settings to limit how much memory Visual Studio can take. If I open two big solutions at the same time, both instances try to take all the available RAM and eventually the whole PC slows down to a crawl.

    In the previous 32-bit versions of Visual Studio, I could do the same without any trouble.

    • Klaus LoeffelmannMicrosoft employee 0

      both instances try to take all the available RAM and eventually the whole PC slows down to a crawl.

      It’s super difficult to remotely diagnose, since so many factors can influence the outcome here.
      I just tried to hold the WinForms runtime and the WinForms Designer solutions side by side on an ARM Surface X (16 GByte), and it did not noticeably slow down. Same on my older Surface Book 2 (also 16 GBytes). Both not the quickest machines these days for that, but also not slower when 2 solutions are open. In fact, after a while, the Surface Book 2 considerably slowed down because of thermo throttling, when I compiled both solutions at the same time, and clocked down under 1 GHZ (!) at times. But that’s not due to memory issues, but rather that the heat couldn’t get out of the board quickly enough. It became REALLY hot, and I guess the fan vents need some urgent cleaning?

      So, there could be so many things to check, I wouldn’t know how to give useful advice without way more context.
      I don’t think though, that this is at all VS related.



  • Josh Tefay 1

    Hi Klaus, is there a way to leverage this Out-Of-Process designer hosting technique in our own applications?

    We have many scenarios were this would be useful, in order to work around the .NET Framework/.NET Core SXS in same process limitation.

    • Klaus LoeffelmannMicrosoft employee 0

      Hey Josh,

      sorry for the late reply.
      We are utilizing JSON RPC internally to communicate between the processes. We were considering Shared Memory for a while, but since also wanted to keep the door open for another use case (not inter-process but also between machines), we gave up on that idea. The infra we build around the internal communication is not public, but my guess is, since it’s specialized for our use case, it also wouldn’t be very reusable in other domains.
      But take a look at JSON RPC. Maybe you find it useful for your use cases?

      Hope that helps!


  • Ulf Emsoy 0

    I’m experiencing that any .NET 6 WinForms applications compiled “Any CPU” only executes 32-bit in Microsoft Store on 64-bit Windows. Have you experienced the same, and/or do you have any suggestions on how to fix the issue?

    • Klaus LoeffelmannMicrosoft employee 0

      Let me check, if I understood you correctly:
      You’ve published a WinForms App in the Microsoft Store, which has been compiled as Any.
      But when you install it from the store, it only runs 32-Bit – did I get that correctly?

      I remember (very vaguely, so, disclaimer! 🙂 this is more an assumption than real knowledge!) from my Pre-Microsoft-Consultant time that you needed dedicated binaries for 32-Bit, 64-Bit, ARM – and so on. If that’s still the case, did you do that?



      • Ulf Emsoy 0

        Hi Klaus,

        Yes, you are correct.

        The “Windows Application Packaging Project” (msix) for .NET 6 does not seem to allow dedicated binaries for 32-bit/64-bit and ARM. It requires “Any CPU”.

        • Ulf Emsoy 0

          After som clean-up of the project files I was eventually able to build a MSIX package combining x86, x64 and ARM64 that solved the issue. Thank you for yout tip.

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