Why legacy .NET Framework is becoming a business risk, not just a technical one
Many organisations are still running critical applications on .NET Framework versions 4.5.2 through to 4.8.1. While .NET Framework 4.8/4.8.1 remains tied to the Windows lifecycle for security patches, Microsoft is no longer adding new features, language updates or performance improvements to it. Development focus has moved entirely to the modern .NET ecosystem , rebranded from .NET Core to simply.NET (from .NET 5 onwards).
This does not mean you need to abandon your existing applications overnight. It does mean that staying on legacy technology for too long can start to limit performance, scalability, future development and, increasingly, your security position, particularly as dependencies age and skilled support becomes harder to find.
We treat migration to .NET as more than a technical upgrade. It is an opportunity to modernise how an application performs, scales and integrates with the rest of your business.
Signs it may be time to move to modern .NET
Outdated/Unsupported
Your team is relying on an outdated or unsupported version of .NET Framework.
Inefficiencies
Development and maintenance are becoming slower or more difficult.
Performance issues
You are experiencing performance or scalability issues as usage grows.
Cloud migration
You are planning a move to the cloud, or want to reduce infrastructure and licensing costs.
Third-party dependencies
Your application depends on older third-party libraries that limit flexibility.
Future Scalability
You have new functionality planned that legacy architecture cannot easily support.
What is the impact?
lower cloud costs on average reported following a .NET Framework - .NET migration
improvement in performance reported following a .NET Framework - .NET migration
increase in mentions surrounding operational risks of .NET Framework YoY
What migrating to modern .NET means for your business
Modern .NET is built to be cross-platform, cloud-ready and designed for long-term development, unlike .NET Framework, which remains tied closely to Windows. For your business, this typically translates into:
Modern .NET is built for speed, supporting applications that need to do more with less infrastructure.
Better suited to applications that need to grow with demand.
Support across multiple operating systems, rather than being locked to Windows.
Full cross-platform support means applications can run on Linux and in Docker containers, which can meaningfully reduce Windows Server and licensing costs compared with staying on .NET Framework.
Reducing the growing cost and risk of supporting ageing dependencies, and keeping you inside Microsoft's supported release window rather than racing an end-of-support deadline.
Our approach to .NET migration
01
Assess
01
Assess
We review your current application, its dependencies, and your business requirements to understand what a successful migration needs to achieve.
02
Plan
02
Plan
We identify any compatibility issues and agree the target version and migration approach with you before any work begins.
03
Migrate
03
Migrate
We update your application, dependencies and architecture in line with the agreed plan.
04
Test
04
Test
We test thoroughly to confirm your application performs as expected, with performance and security maintained throughout.
05
Deploy & Optimise
05
Deploy & Optimise
We move your application into its new environment and identify where modern .NET can add further value.
Not every application follows the same migration path
Some applications can be upgraded relatively quickly. Others, particularly those built on older architectures, may need more significant redevelopment. Our approach adapts to the technology you are already running.
Our .NET engineers will review your technical stack, code structure and any existing technical debt to understand the best migration path to fully transform your .NET ecosystem. We will provide a full digital transformation roadmap unique to your business and designed to scale as your organisation evolves.
Common questions about .NET migration
Not necessarily, though timing depends on which version you are running. .NET Framework 4.8 remains within Microsoft's Windows lifecycle support, so moving off it is a strategic decision for most businesses. We can help you assess where your application sits and what timeline makes sense.
We plan and test every stage to minimise disruption, and agree deployment timing that works around your business.
Yes. We can lead the migration end to end, or work alongside your internal team to provide additional capacity and specialist expertise where it is needed.
This is common, and part of what we assess early on. We identify where dependencies need updating or replacing as part of the migration plan, including data access layers built on older Entity Framework/EDMX models and services built on WCF, both of which need a specific migration route onto modern .NET.
Often, yes. Because modern .NET runs on Linux as well as Windows, many organisations use migration as an opportunity to move workloads onto Linux or Docker containers, which can reduce Windows Server and licensing costs. We can factor this into your migration plan if cost reduction is a priority.
Yes. We provide ongoing software support and maintenance once your application is live on modern .NET.
Modernising .NET for the future
Migrating from .NET Framework to modern .NET is not just about keeping up with technology. It is an opportunity to improve performance, flexibility and maintainability, while building a stronger foundation for what your business needs next.