Convert VB6 to .NET: Strategies, Challenges, Actuality

Why are business leaders thinking about converting VB6 to .NET?
Visual Basic was introduced by Microsoft in 1991 and became very popular across most large-scale enterprises. A lot of applications of that period were based on the well-known programming language.
But later, as Microsoft has abandoned Visual Basic in favor of the .NET Framework, some things have changed. The last, final release was the version 6 in 1998.
Visual Basic 6.0 IDE is not supported anymore, and according to Microsoft, Windows supports core functionality that is “used in the majority of scenarios”.
Should you convert VB6 to .NET?
Is now the time to modernize legacy systems built upon VB6 code? The short answer’s yes.

But why? Let’s find out more.
Microsoft’s support does not cover everything, which leads to crashes and broken third-party components. Many vendors do no longer support outdated applications, making modernization a critical business necessity.
Business companies must rewrite their applications, as further delaying modernization will only multiply risks. The 2020 COBOL crisis showed how outdated applications can become expensive liabilities over time.
To date, finding talented VB programmers is difficult since most have moved to more modern technologies. With fewer VB experts, legacy applications become unsustainable.
Old architectures can create various issues, for example spaghetti code, thus complicating daily maintenance. And that’s only one tiny part of all the risks to expect.
How to convert VB6 to .NET: the most popular strategies
Now, what can we do when a company is ready to start a transition to more modern technologies?
- VB6 extension
- Visual Basic 6 migration
- Visual Basic 6.0 rewriting
Let’s discuss every one of them in detail to efficiently convert VB6 to .NET.
Modernize VB6 to .NET: extension strategy
This VB6 to .NET conversion strategy is best-suiting in case:
- The application works fine
- The issues and risks coming with legacy systems are acceptable
- You need to develop new features but with fewer effort
When approaching VB6 code migration projects, .NET modules can be called additionally from within old apps. You can leave the legacy code as is but implement new stuff with some modern framework.
Old modules that are still relevant to fundamental business operations can be also migrated to the new system. This approach is well-known as the “strangler” pattern.
The advantages of the extension strategy:
- It might be the cheapest way in the short term
- The process is gradual
The disadvantages of the extension strategy:
- Potential risks associated with business continuity
To facilitate the process, you can use a Visual Basic migration tool for extension, for example:
- Code Architects’ VBMigration Partner
- Great Migrations’ VB6/ASP to .NET Migration Toolkit
- Micro Focus’ Visual Basic Upgrade Companion
- Cognosys Inc. VB6 to .NET Migration Toolkit
There are also other VB6 to .NET migration tools available, but it is important to review the existing legacy codebase before choosing.
Modernize VB6 to .NET: migration strategy
This type of Visual Basic upgrade is the best match in case:
- The application works unstably
- The users are facing frequent errors, which sometimes even cause work loss
- Business processes are attuned to the desktop experience
Abto Software has both broad knowledge and experience in implementing the described migration strategy – for example, we converted VB6 to .NET code for a charity platform for an international company.
The advantages:
- VB6 migration to .NET is the second cheapest modernization way after the extension approach
- The application will be completely free from potential security and stability issues
The disadvantages:
- The application is developed before the new functionality is added
- Poor architecture might be potentially inherited from the source code and eliminating this problem might require extra efforts
Modernize VB6 to .NET: rewriting strategy
This type of Visual Basic upgrade is the best match in case:
- The conversion is done from the legacy desktop VB6 application
- The company is aiming at extending market share
- The application is now totally outdated
As a striking example, Abto Software has implemented this approach when working with a large retail company – our team has modernized and migrated a legacy ERP platform.
The advantages:
- The change of platform to web or mobile is the only way to go
- An architecture that’s written from scratch by using modern approaches is cheaper
The disadvantages:
- It requires a bigger initial investment than the previous strategies
- The functionality must be extensively tested for compliance with the old behavior
The benefits of converting from VB to .NET
Higher performance and efficiency
- Optimized runtime (Just-In-Time compilation)
- Faster execution with multi-threading
- A better memory management
- Garbage collection
- Increased reliability
- Reduced downtime
Expanded functionality and scalability
- The access to the .NET ecosystem, including libraries and APIs
- The support for microservices and modern modular architecture
- The ability to handle increased workloads
- Load balancing
Improved security through updates and patches
- Regular updates and patches
- Built-in authentication and authorization
- Protection against common vulnerabilities
- Regulatory compliance
Enhanced compatibility across platforms and devices
- Cross-platform support (.NET Core, .NET 5+)
- Native support (Windows, Linux, and macOS)
- Seamless integration with both mobile and web applications
- API connectivity with modern third-party services and tools
Long-term support and maintenance
- Ongoing enhancements from Microsoft
- Large community and support for troubleshooting
- Easier debugging and refactoring (Visual Studio, JetBrains Rider)
- Future-proof platform
Cloud compatibility
- Serverless computing
- Native support for popular cloud platforms
- Scalable and distributed applications with Kubernetes and Docker
- Secure storage, disaster recovery, and backup
The challenges of converting from VB to .NET worth knowing
As we already mentioned, there are numerous challenges with supporting and maintaining VB6 applications. For example, you will hardly find suitable candidates that possess Visual Basic programming knowledge – obtaining exhaustive Visual Basic programming experience is simply not profitable.
If you are about to modernize a legacy VB6 application, you have to consider a lot of things except strategies. You need to find and assemble a team to perform Visual Basic conversion smoothly.
What about VB6 to C# conversion?
To learn more about how to migrate from VB6 to C# code, surf our blog articles.
The tools worth considering before you convert VB6 to .NET
There are automation tools specifically designed to assist in converting VB6 code to the .NET environment. These popular third-party tools might streamline the process by translating VB6 code into appropriate, compatible components within the modern platform.
They minimize manual effort, speed up software development, and also minimize potential human errors. However, remember that additional manual adjustments are needed to optimize application performance, improve reliability, enhance maintainability, and integrate new features.
You can learn more about the best tools in our detailed overview, but let’s discuss those briefly below:
The VB Migration Partner
Key characteristic:
- Fine-grained conversion, preserving patterns and behavior
- High accuracy, with attention to maintaining legacy structure and behavior
- Extensive customization, custom converters and directives
- Extensive documentation and tutorials, sample projects
Best-fitting cases:
- Different-scale projects that require extensive control
- Complex applications with sophisticated business logic and unique code structures
Visual Studio Upgrade Assistant
Key characteristic:
- Direct conversion
- Moderate accuracy, with focus on transitioning to modern C# code
- Limited customization possible through command-line options
- Microsoft Docs, community contributions
Best-fitting cases:
- Existing projects that transition from older .NET versions to newer .NET Core/5/6/7
- Specific scenarios:
- .NET applications that require an upgrade
- VB6 applications that require basic conversion
Visual Basic Upgrade Companion
Key characteristic:
- Detailed conversion, extensive analysis
- High accuracy, with focus on preserving legacy functionality and performance
- Extensive customization, custom rules and adjustments
- Extensive documentation and tutorials, case studies
Best-fitting cases:
- Large-scale projects, including complex and extensive VB6 applications
- Complex applications that include third-party controls and large legacy codebases
Why choose custom solutions over tools when you convert VB6 to .NET?
Going with custom solutions for your VB6 to .NET conversion might facilitate greater flexibility and scalability. Unlike using available tools, which follow predefined workflows, this strategy can address unique objectives – business logic, complex architecture, and other, business-specific requirements.
When choosing custom solutions, you prioritize critical components during smooth VB6 to .NET conversion. What’s more, this approach also allows code optimization and refactoring, better performance and scalability, and alignment with long-term business goals.
Convert VB6 to .NET: best practices
Code audit
It’s essential to check your application, no matter the strategy you’ve chosen: extension, migration, or rewrite. For example, are there any lines that don’t belong there?
Quite possible, you’ll need a team that has Visual Basic programming experience to clean up the final code.
Third-party controls
There are some irrelevant third-party controls being used with the latest version of the outdated environment. If you continue using those components, it will slowly decrease your performance and speed.
Once again, to handle incompatible components, you should consider hiring a team that has Visual Basic programming experience.
Quality control
If the legacy code is unclear and has pressing issues, the best possible decision is probably rewriting everything. By converting poor code, you’ll have to spend way too much time and cost on troubleshooting.
Bug fixing
This step is obvious, but still – careful preparation will help to minimize the number of problems to encounter. Don’t postpone this step or else your end-user’s will have an undesirable user experience.
Success stories
Belt-drive systems engineering toolkit
During this long-term partnership, Abto Software was helping a known business leader in the machinery domain – our engineers successfully modernized mathematically complex legacy applications.
Abto Software was contracted to migrate outdated technologies (VBA, VB6, and LISP) to the .NET framework. Moving further, our team also provided cross-platform compatibility and implemented advanced functionality to streamline business productivity.
Our client now enjoys:
- Lower license costs
- Resolved runtime issues
- Optimized employee training
- Minimized maintenance costs
CRM upgrade, from desktop to cloud
Working within this partnership, Abto Software was assisting an organization that helps overcoming poverty and provided CRM modernization to make the platform more convenient and reliable.
Abto Software has entered the project to cover CRM modernization and benefit 14 offices all over the globe. Besides migration, our team has covered UI/UX improvements, CRM centralization, and migration to cloud.
Our client immediately obtained:
- An enterprise-level CRM software for straightforward remote workflows
- Intuitive and responsive design
- Improved performance
- Enhanced security and sustainability
- Process automation
- Hassle-free maintenance
How we can help
Abto Software, a VB6 migration partner, has proven tech expertise for transitioning mission-critical applications.
Our engineers handle discovery and planning, code assessment and preparation, and smooth VB6 migration. Our clients forget about operational and performance shortfalls, security vulnerabilities, compatibility issues, and other common challenges coming with legacy modernization.
Our services:
- AI development
- RPA services
- .NET development
- ASP.NET development
- Web development
- Mobile development
- Cloud services
- Custom product software development
Our expertise:
And, particularly, VB6 migration expertise proven over and over again!
FAQ
When calculating project costs, your partner might consider various factors besides complexity and approach. These include desired functionality, quality assurance, customization, enhancements, support, maintenance, and even documentation management.
When estimating project timelines, your contactors might assess different factors, both internal and external. These include code quality and structure, team size and expertise, resource availability, decision-making speed, and specific project nuances, for example compatibility issues.
Code conversion, if not approached professionally, can cause various problems and affect overall performance. These problems might include dependency conflicts, deprecated functions and libraries, and many other issues.
That’s why it’s important to work with providers that have proven expertise in handling associated challenges. For example, in debugging issues efficiently.
Code conversion, speaking about outdated applications, comes with different challenges and bottlenecks. Memory leaks, management issues, runtime errors, database problems, and others.
Even after successful conversion, these challenges might emerge and deteriorate business-specific operations. To eliminate potential damage, we recommend testing after, as well as ongoing technical support and maintenance.

