Short answer: .NET 11 reaches general availability at .NET Conf 2026 (November 10–12, 2026), following RC1 on September 8 and RC2 on October 13, 2026, both carrying a go-live license for production use. It ships with C# 15, which adds union types and closed hierarchies, plus runtime, validation and EF Core improvements. For business owners the more urgent date is November 10, 2026, when both .NET 8 and .NET 9 reach end of support.
Where .NET 11 stands today
Microsoft ships a major .NET release every November. Even-numbered releases are Long Term Support (LTS, three years); odd-numbered releases are Standard Term Support (STS, two years). That makes .NET 11 an STS release, while .NET 10 remains the current LTS.
| Release | Support type | Status / date |
|---|---|---|
| .NET 8 | LTS | End of support November 10, 2026 |
| .NET 9 | STS | End of support November 10, 2026 |
| .NET 10 | LTS | Supported until November 14, 2028 |
| .NET 11 RC1 | Go-live | Released September 8, 2026 |
| .NET 11 RC2 | Go-live | Released October 13, 2026 |
| .NET 11 GA | STS | Launch at .NET Conf, November 10–12, 2026 |
C# 15 in brief
C# 15 is the default language version for net11.0. Apart from the new memory-safety rules, none of its features require preview opt-in.
Union types
The new union keyword declares a type that holds a value from one of several case types, with implicit conversions and compiler-checked exhaustive switch expressions. In business software this is a clean way to model outcomes such as “invoice accepted”, “rejected with reason” or “pending review”. System.Text.Json serializes unions, and OpenAPI documents them as anyOf.
Closed hierarchies
The closed modifier restricts derivation to the declaring assembly, so the compiler knows every subtype and a switch needs no default arm. Document lifecycles (draft, approved, posted, voided) become safer to model.
Smaller quality-of-life features
- Collection expression arguments via a leading with(…) element.
- Extension indexers inside extension blocks.
- Labeled break and continue, replacing flag variables and goto.
- Non-virtual static interface members on older runtimes.
- Updated memory-safety rules (preview).
Platform highlights
- Runtime: runtime-native async for net11.0 with cleaner stack traces and lower overhead; JIT bounds-check elimination and devirtualization improvements; faster NativeAOT interface dispatch.
- Libraries: built-in Zstandard compression, Decimal32/Decimal64/Decimal128 types, LINQ FullJoin, async validation through IAsyncValidatableObject, and experimental ML-KEM post-quantum cryptography.
- ASP.NET Core and Blazor: client-side validation for static SSR forms by default, async form validation, QuickGrid URL-based paging and sorting with OnRowClick, variable-height Virtualize, and built-in validation localization for Minimal APIs.
- EF Core 11: experimental vector indexes and vector search for SQL Server 2025, full-text index management in migrations, new JSON functions, and up to 29% faster split queries per Microsoft’s documentation. Note that UseSqlServer now defaults to compatibility level 160.
- .NET MAUI and tooling: MAUI moves to CoreCLR on Android, iOS and Mac Catalyst; dotnet test supports mobile projects; and the new dotnetup tool (public preview, announced October 15, 2026) installs SDKs without admin rights.
What this means for Saudi businesses
- Apps on .NET 8 or 9: security patches stop on November 10, 2026. For critical systems, move to .NET 10 LTS (supported to November 2028).
- New projects: start on .NET 10 LTS, or on .NET 11 if C# 15 and the new Blazor features matter and you accept a two-year upgrade rhythm.
- Integrations: services that talk to e-invoicing platforms or e-commerce stores should always run on a supported, patched runtime.
- Budget: upgrading between modern .NET versions is usually far cheaper than a rewrite, but financial calculations, VAT rounding and reports need regression testing.
Pre-upgrade checklist
- Inventory every app and service and its target framework.
- Confirm third-party library support for .NET 10 or 11.
- Review EF Core breaking changes, especially the SQL Server compatibility-level default.
- Automate tests for accounting logic and 15% VAT calculations.
- Deploy off-peak with a clear rollback plan.
How the Riv-ERP team can help
Riv-ERP is a Saudi-made cloud ERP and accounting system built on Oracle Database and Oracle APEX, compliant with ZATCA e-invoicing Phases 1 and 2. Alongside it, the team builds custom solutions with .NET, C#, SQL Server and Blazor; the founder is a developer in this stack and the team brings 20+ years of experience. If you have an internal .NET 8 system to upgrade or an integration to build, request a quote or reach our Jeddah team on WhatsApp at +966552007190.
Sources: What’s new in .NET 11, What’s new in C# 15, .NET support policy, .NET Conf 2026 announcement.
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Frequently Asked Questions
When is .NET 11 released?
.NET 11 launches at the online .NET Conf 2026, November 10–12, 2026. RC1 shipped September 8 and RC2 October 13, 2026, both with a go-live license.
Is .NET 11 an LTS release?
No. Odd-numbered releases are STS with two years of support. .NET 10 is the current LTS, supported until November 14, 2028.
What happens to .NET 8 apps after November 10, 2026?
They keep running but receive no further security fixes from Microsoft, so plan an upgrade to .NET 10 or .NET 11 as soon as possible.
Which C# 15 feature matters most for business software?
Union types and closed hierarchies, because they let the compiler verify that every document state or operation outcome is handled, reducing logic errors in approval and posting workflows.
Do I need SQL Server 2025 to use EF Core 11?
No. EF Core 11 works with earlier SQL Server versions, but vector search and the JSON_CONTAINS translation require SQL Server 2025 at compatibility level 170.
Can Riv-ERP upgrade our in-house .NET system?
The Riv-ERP team builds custom .NET, C#, SQL Server and Blazor solutions and can assess your system, propose an upgrade plan and quote after an initial conversation.
