.NET 10 LTS landed on November 11, 2025, and it’s supported through November 2028. If you run production on .NET 8 or 9, the clock just started. This guide cuts the marketing gloss and focuses on what .NET 10 LTS changes for teams building web backends, APIs, and data‑driven services—and how to upgrade in 45 days with confidence.

.NET 10 LTS support window visual on calendar next to code

What’s new in .NET 10 LTS that changes your roadmap

Let’s anchor the essentials. .NET 10 is an LTS release with three years of fixes and security updates. Alongside the runtime, you get C# 14, ASP.NET Core 10, EF Core 10, updated libraries (including post‑quantum crypto APIs and networking), and first‑class improvements for NativeAOT and containers. Visual Studio 2026 ships with support out of the box, and the support policy extension for odd‑numbered releases means .NET 9 exits support on November 10, 2026, just 12 months after .NET 10 GA. Translation: production should aim for .NET 10 LTS, not hold on STS unless you’re prototyping.

Highlights you’ll feel in real apps:

Performance: JIT inlining and devirtualization improvements, better Arm64 behavior, and NativeAOT gains translate to lower latency and memory on services under load.
Security and cryptography: expanded post‑quantum cryptography primitives and TLS improvements across platforms.
ASP.NET Core 10: passkey (WebAuthn/FIDO2) support in Identity templates, richer diagnostics and metrics, and server‑sent events helpers.
C# 14: field‑backed properties, extension members, null‑conditional assignment, more Span conversions—quality‑of‑life features that reduce boilerplate and allocations.
EF Core 10 + SQL updates: built‑in support for SQL Server 2025 vector data type and JSON data type (with JSON indexes), plus named query filters and other LINQ enhancements.

Should you upgrade to .NET 10 LTS now or wait?

Here’s the thing: many teams hesitate until the first or second monthly servicing update. That’s reasonable for risk‑averse estates—but the delta between .NET 8 and .NET 10 is purposeful, not chaotic. If you’re on .NET 8 LTS with healthy tests, you can move a representative API within a sprint. If you’re on .NET 7 or earlier, you’ll need an extra pass for dependency alignment and a modest refactor budget for trimming/NativeAOT compatibility and Identity changes.

When should you wait? If your service relies on niche libraries that haven’t published net10‑targeting packages, or you depend on platform‑specific shims that aren’t AOT‑safe, hold a few weeks while you validate alternatives. Otherwise, every month you delay you’re giving up performance headroom and stretching your migration into the next deadline.

What exactly changed in ASP.NET Core 10?

Three changes map directly to real‑world outcomes.

Passkeys built in. ASP.NET Core Identity now supports passkeys (WebAuthn/FIDO2). For apps with recurring password resets, this moves the needle on both conversion and security. The Blazor Web App template wires passkey registration and login out of the box.
Diagnostics you’ll actually use. New metrics for Identity, auth, Blazor, and memory pools plus improved Blazor Server tracing make it easier to detect hot spots and regressions before customers do.
Streaming and responses. A typed result for server‑sent events simplifies real‑time status updates without upgrading to full WebSockets. And the ProblemDetails integration is easier to standardize across teams.

Data layer advances: EF Core 10 meets SQL Server 2025

Two data platform features justify attention.

Native JSON type and JSON indexes. SQL Server 2025 and Azure SQL now support a native JSON type (with JSON_OBJECTAGG/JSON_ARRAYAGG) and a JSON index. EF Core 10 recognizes the capability and can map complex types and primitive collections to JSON columns, producing strong performance and safer storage than nvarchar hacks. If you’re modeling user preferences, small documents, or denormalized aggregates, this reduces joins and improves query ergonomics.

Vector search. SQL Server 2025 adds a vector data type and vector search functions. EF Core 10 exposes the type and lets you compose similarity queries in LINQ using distance metrics. For teams building RAG or semantic features, this keeps your embeddings and relational data in one transactional store (with enterprise ops), avoiding a separate vector DB for many scenarios.

C# 14: small features, big payoff

Field‑backed properties give you a clean upgrade path from auto‑props to custom logic without ceremony. Extension properties and static extension members open up utility patterns you’d have avoided before. Null‑conditional assignment trims a surprising amount of guard code. You won’t rewrite your codebase for these, but over hundreds of properties and helpers, the readability and allocation wins are real.

Performance wins you can bank on

Expect lower P99 latency for CPU‑sensitive endpoints and better throughput on Arm64 machines. The runtime’s inliner and devirtualizer keep getting smarter; memory pools evict more predictably; and NativeAOT trims distribution size and warm‑start times. If you serve bursty traffic or large fan‑out calls, measure again—your autoscale thresholds may be conservative now.

The 45‑day .NET 10 LTS upgrade plan

Use this as a playbook you can hand to a tech lead today.

Days 0–5: Decision and scoping

Pick two canary services: one API on your hottest path, one Blazor or background worker. Define exit criteria: deploy on .NET 10, same or better P95/P99, error rate unchanged, and no critical logs/regressions for 72 hours.
Install the .NET 10 SDK and upgrade local IDEs or devcontainers. If your org standardizes on Visual Studio, align on 2026.
Create an upgrade branch and set target frameworks to net10.0. Keep the old TFM in <TargetFrameworks> if you must ship hotfixes in parallel.
Turn on build analyzers that matter: nullable, trimming warnings, and CA rules you actually enforce.

Architecture diagram: ASP.NET Core 10 with EF Core 10 JSON and vector support

Days 6–15: Dependency reality check

Run dotnet list package --outdated and update transitive dependencies. Prefer providers that already publish net10.0 and AOT‑safe annotations.
Adopt the SDK’s package pruning defaults and re‑baseline NuGet audit. Expect fewer false positives; note any missing framework‑provided references your build assumed.
For NativeAOT candidates, audit reflection hotspots. Replace dynamic serializers with source‑gen, and avoid runtime codegen in request paths.

Days 16–30: Code and behavior changes

Identity: if you roll your own UI, wire passkey enrollment and sign‑in. For multi‑tenant apps, validate RP ID and origin settings in every environment.
JSON serialization: enable “disallow duplicate properties” and your chosen strictness—then run integration tests that parse external payloads. Fix callers that relied on last‑write‑wins quirks.
EF Core 10: if you’re on SQL Server 2025 or Azure SQL with the capability enabled, move eligible aggregates to JSON columns with a JSON index and benchmark. For AI features, add a vector column and a similarity endpoint; verify compute costs under your normal concurrency, not synthetic single‑user tests.
Observability: adopt the new ASP.NET Core metrics and wire them to your OpenTelemetry pipeline. Alert on stale memory pools and Blazor circuit anomalies.

Days 31–45: Production hardening

Re‑tune thread pool and Kestrel limits only if data says so. Most apps benefit from the defaults in .NET 10.
Publish container images from dotnet publish with explicit image format; sanity‑check SBOM and scan results.
Blue‑green or canary: deploy to 5% traffic for 24 hours, then 25%, then 100% with rollback gates tied to error budget and latency SLOs.
Sunset the old TFM in your mainline. Archive the branch and remove conditional code paths within a week to avoid configuration drift.

Risks, limitations, and edge cases

Every upgrade has sharp edges. Here are the ones we’ve repeatedly seen:

Reflection and AOT. Libraries that emit IL at runtime often fail under NativeAOT. Keep those services on JIT (regular publish) or replace with source‑generated alternatives.
JSON behavior. Stricter options can surface payload issues from upstream services. Decide whether to reject invalid input or accept and log, but don’t silently coerce without audit trails.
Passkeys across environments. Mismatched origins will fail silently in some frontends. Treat RP IDs as infrastructure code and test on every domain and subdomain you serve.
EF Core provider features. JSON type and vector search require specific database compatibility levels. If you target older SQL Server instances, EF Core will fall back to prior behaviors—but your performance assumptions may no longer hold.
Package pruning surprises. If you referenced framework‑provided assemblies implicitly, builds may break after pruning. Add explicit references or update targets.

Let’s get practical: a one‑page .NET 10 LTS upgrade checklist

Target net10.0 and upgrade build images/agents first.
Update dependencies; prefer packages with AOT support and net10.0 builds.
Enable stricter JSON settings and fix failing payloads.
Adopt ASP.NET Core 10 metrics; wire up passkeys if you use Identity.
Benchmark NativeAOT candidates; stick to JIT for heavy reflection.
Migrate hot aggregates to JSON columns and index them; evaluate vector search if you ship semantic features.
Canary deploy with SLO‑based gates; remove dual‑TFM code swiftly.

Where this fits in your product and budget

Zooming out, this upgrade is a business decision. The performance headroom means fewer nodes or higher margins. The diagnostics reduce MTTR. Passkeys cut support volume. And EF Core 10 with SQL Server 2025 compresses your data stack for AI features you can actually operate. If you’re already planning a feature release in Q1, fold the migration now—don’t stack migrations and feature crunch into the same month later.

Want a deeper playbook or a sanity check?

We’ve published a battle‑tested upgrade guide for large teams in Your .NET 10 LTS Upgrade Playbook (2025). If your biggest risk is CI/CD and supply‑chain safety during the cutover, borrow hard‑won lessons from our GitHub Actions pull_request_target survival guide and our npm token migration cutover notes—different ecosystems, same principles. Need hands‑on help or an external retro on your architecture? See our services overview.

What to do next

Pick two canary services and spin a net10.0 branch today.
Turn on stricter JSON options, wire new ASP.NET metrics, and baseline performance.
Trial passkeys with a small user cohort; measure sign‑in success and support tickets.
Model one JSON column and one vector column in EF Core 10 and capture query timings.
Schedule a canary rollout window with rollback gates and ownership clearly assigned.
If you need a second set of eyes, reach out via Bybowu Contacts.

The bottom line

.NET 10 LTS isn’t a risky rewrite—it’s a disciplined migration with clear payoffs: performance, security posture, simpler auth, better diagnostics, and a cleaner data story for AI features. Ship a canary in the next sprint, prove it with numbers, and move the rest with a tight plan. Your future upgrades will thank you.

dotnet publish and tests passing on .NET 10