Many organisations are still running business-critical applications on .NET 8 and .NET 9. While these platforms remain supported today, both versions reach end of support on 10 November 2026.
Once support ends, organisations will no longer receive security updates, bug fixes, or platform support from Microsoft. This creates security, compliance, and operational risks, particularly for applications that support critical business processes.
Although 10 November 2026 may seem distant, enterprise upgrades often take months to plan, assess, test, and deploy. The organisations that start preparing now will avoid the last-minute rush and reduce migration risk.
You should start planning your upgrade strategy if you:
Run applications on .NET 8 or .NET 9
Depend on legacy NuGet packages
Use third-party libraries with uncertain support roadmaps
Operate customer-facing applications
Run regulated or compliance-sensitive systems
Have multiple applications requiring coordinated upgrades
Many organisations underestimate the effort involved until compatibility issues emerge during testing.
Delaying framework upgrades can result in:
Security Risk: Unsupported platforms stop receiving security updates from Microsoft.
Increasing Technical Debt: The longer an upgrade is postponed, the larger the gap becomes between your application and the supported platform.
Higher Project Costs: Regular, incremental upgrades are typically less costly and lower risk than large-scale migrations after years of accumulated changes.
Business Disruption: Applications operating on unsupported technology can become difficult to maintain and troubleshoot.
Microsoft's .NET 10 overview covers improvements across the runtime, SDK and application frameworks. For many organisations, the most relevant areas include:
.NET 10 continues Microsoft's investment in runtime optimisation, including improvements to JIT inlining, method devirtualisation and stack allocation. Depending on the workload, these changes may improve throughput or reduce resource usage.
The .NET 10 SDK expands container publishing options, including native container image creation for console applications. This can simplify delivery for cloud-hosted workloads.
The .NET 10 SDK adds Microsoft.Testing.Platform support in dotnet test, command-line improvements, and enhanced file-based app publishing. These changes can reduce friction in build and test workflows.
ASP.NET Core 10 includes several platform improvements, such as:
Blazor performance and usability enhancements
OpenAPI 3.1 support and document-generation improvements
Validation support for Minimal APIs
Enhanced diagnostics
Passkey support in ASP.NET Core Identity
For teams using ASP.NET Core, these updates can simplify API development, validation and authentication while improving diagnostic visibility.
.NET 10 is an LTS release, providing support until 14 November 2028 and offering a stable platform for enterprise workloads.
Microsoft documents binary, source and behavioural changes that may affect applications moving to .NET 10. Their impact depends on each application's architecture, dependencies, hosting model and deployment process.
Review Microsoft's .NET 10 breaking changes catalogue before beginning an upgrade. Compatibility analysis and regression testing should form part of every upgrade plan.
A .NET 10 upgrade involves more than changing a target framework. The level of effort depends on dependencies, hosting, test coverage and deployment complexity.
A typical engagement includes:
Current framework review
Dependency analysis
Third-party package review
Infrastructure assessment
Deprecated APIs
Package upgrades
Build pipeline validation
Functional testing
Regression testing
Security validation
Performance testing
Deployment planning
Rollback strategy
Post-deployment monitoring
In our experience, organisations frequently encounter:
Unsupported Third-Party Packages: Some dependencies may no longer be maintained.
Legacy Build Pipelines: Older CI/CD configurations often require updates.
Custom Framework Extensions: Applications that contain framework-specific customisations may need code refactoring.
Testing Gaps: Many organisations lack sufficient automated test coverage to execute large upgrades confidently.
One of the most common issues we encounter during upgrade assessments is not code compatibility but dependency management.
Applications that appear straightforward to upgrade often rely on older NuGet packages, authentication libraries, reporting components, or deployment processes that have not been reviewed for several years.
Identifying these risks early enables organisations to create realistic delivery plans and avoid surprises during implementation.
The 10 November 2026 deadline is now close enough that assessment and planning should already be underway.
Organisations running .NET 8 or .NET 9 should start assessing their application estate now to avoid security risks, technical debt, and last-minute migration pressure.
A well-planned move to .NET 10 can also create an opportunity to improve performance, strengthen security and modernise infrastructure.
If you're unsure what the 10 November 2026 support deadline means for your applications, DSP can help.
We can review your:
Current target frameworks
Third-party dependencies
Build and deployment processes
Infrastructure configuration
Upgrade complexity and risks
We then provide a prioritised .NET 10 Upgrade Readiness Assessment with practical recommendations and next steps.
Contact DSP to request a .NET 10 Upgrade Readiness Assessment and identify the highest-priority risks across your applications before the support deadline.