What .NET 10 LTS Changes for Your Web Stack

.NET 10 LTS is now generally available, with three years of support running through November 10, 2028. For web teams, that window matters: you can modernize authentication, ship real‑time UX with fewer moving parts, and pick up performance gains without re‑platforming. This piece zeroes in on what .NET 10 LTS actually changes for ASP.NET Core, EF Core, and your CI/CD story—and how to adopt it with minimal risk.

Why .NET 10 LTS is worth your time (and budget)

Let’s get the calendar straight. .NET 10 is an LTS release with support until November 10, 2028. Microsoft also extended odd‑year STS releases to 24 months, which means .NET 9 stays supported until November 10, 2026—but that’s still a relatively short runway for production teams. If you’re sitting on .NET 6 or 7, you’re already feeling patch pressure; if you’re on .NET 8, you’ve got a year to plan before its LTS window closes in 2026. The point: production workloads that value stability should target .NET 10 LTS now rather than waiting for a scramble in late 2026.

Beyond dates, .NET 10’s runtime and SDK deliver concrete wins: improved JIT and NativeAOT, new APIs for networking (like a WebSocketStream that makes streaming I/O simpler), and developer‑experience upgrades in the CLI and test infrastructure. But the biggest changes for web apps land in ASP.NET Core and EF Core.

ASP.NET Core 10: the upgrades you’ll actually use

The headline improvements in ASP.NET Core 10 align with what teams have been building toward for years: secure sign‑in without passwords, simpler real‑time streams, and better first‑party diagnostics.

Highlights that move the needle:

• Passkeys (WebAuthn/FIDO2) in ASP.NET Core Identity. You can offer phishing‑resistant passwordless sign‑in without third‑party packages. The default Blazor Web App template wires this up end‑to‑end, but it’s Identity functionality—not Blazor‑only—so MVC and minimal API projects can adopt it with the right Identity schema version and UI wiring.
• Server‑Sent Events via TypedResults. A native ServerSentEvents result lets you stream updates to the browser with one HTTP connection. For live notifications, logs, or dashboards, SSE is simpler than WebSockets and avoids a SignalR dependency when you only need one‑way updates.
• Better defaults for auth and validation. Minimal APIs get built‑in validation, and you can standardize error shapes with IProblemDetailsService. Identity and auth emit more metrics out of the box, so your observability finally covers the login funnel and token flows without custom counters.
• Memory pool eviction and tracing upgrades. Long‑running processes leak less memory, and Blazor diagnostics tell you what a circuit is doing when it misbehaves. These are the quality‑of‑life improvements SREs have been asking for.

Put it together and you can modernize sign‑in, cut code for basic real‑time UI, and get a clearer picture in production, all within the framework. That’s the definition of a safe LTS value add.

EF Core 10: AI‑ready data with vectors and native JSON

EF Core 10 ships features that matter in 2025’s data patterns. If you’re leaning into retrieval‑augmented generation (RAG) or recommendation features, you’ll appreciate first‑class support for vector scenarios on platforms that expose a vector type and distance functions. And with Azure SQL and SQL Server 2025 introducing a native JSON type plus JSON indexes, EF can map documents without the nvarchar(max) hacks of old. That means safer schema, faster queries, and fewer computed columns just to index nested fields.

Two practical implications for teams:

• Simpler semantic search. Storing embeddings next to your relational data avoids an extra vector store to run and secure. You can prototype rankings using cosine distance in pure SQL and promote to approximate search as needed.
• Governable schemaless. With a native JSON type, you can evolve payloads without explosions of tables, while still enforcing constraints and indexing hot paths. Migrations become boring again.

C# 14 and the little things that add up

C# 14 isn’t flashy, but it removes friction. Field‑backed properties let you evolve from auto‑props without verbose backing fields. Extension members (including properties) reduce boilerplate across types you don’t own. Span conversions become more natural for high‑performance code paths. In aggregate, these improvements trim code and make refactors safer—exactly what you want paired with an LTS platform upgrade.

Security reality check: why upgrading still matters

In October, Microsoft patched a critical request smuggling vulnerability in Kestrel (tracked at 9.9 severity). The ecosystem responded quickly, but incidents like this are a reminder: the parts of your stack that face the internet need current runtimes. .NET 10 LTS rolls forward the fixes, and the team also improved defaults and diagnostics around auth, redirects, and error handling. If you’re running public APIs, this is a strong nudge to consolidate on a supported line with predictable patch cadence.

“Should we upgrade to .NET 10 LTS now?”

If you own revenue‑critical websites or APIs, yes—plan the rollout this quarter. The changes are incremental (not a rewrite), and the benefits compound: passkeys reduce account‑takeover risk and support load, SSE removes custom plumbing for one‑way real‑time UX, EF Core 10 aligns your data tier with AI features you’re likely to pilot in 2026, and the runtime is simply faster. Teams on .NET 8 LTS can keep a steady pace; teams on older versions should prioritize migration to land before late 2026.

Hands‑on: a tiny blueprint for passkeys + SSE

Here’s the thing: it’s easy to talk about modern auth and real‑time without ever shipping it. A practical starter pattern looks like this:

• Authentication: Enable ASP.NET Core Identity with passkeys. Start by scaffolding the Identity UI (or the Blazor template), update the schema to include the passkey table, and light up registration and sign‑in flows. Keep passwords as a fallback; measure passkey adoption over 30 days.
• Real‑time: For admin dashboards and “events” pages, expose an SSE endpoint that streams a typed event every few seconds. Use browser EventSource to display updates. No hand‑rolled websockets, no extra servers.
• Observability: Hook the new Identity and auth metrics into your telemetry provider, set SLOs on login success rate, and alert on spikes in challenges/failures.

Do this in a feature branch, run it in a canary slot, and you’ll learn more in a week than a month of debate.

Migration pitfalls and tradeoffs no one advertises

Upgrades fail when we ignore edges. Watch for these:

• Preview bits lurking in prod. Make sure any pre‑release packages you tested in previews are replaced with final versions. Don’t assume transitive dependencies got the memo.
• EF Core defaults around native JSON. On Azure SQL and SQL Server 2025, EF Core 10 can adopt the new JSON type by default under certain compatibility levels. That’s good for performance, but it will generate migrations—plan the change, especially if you replicate data or depend on string semantics.
• Validation and ProblemDetails changes. If you’ve shipped custom error envelopes, align them with the new validation hooks so clients don’t get surprised by shape changes.
• Auth redirects for APIs. API endpoints shouldn’t bounce to login pages. Confirm your auth settings return 401/403 instead of redirects, and pin tests for this.

How we’d roll out .NET 10 LTS in a real team

Here’s a simple, sprint‑friendly plan my teams use.

The 10–10–10 Upgrade Sprint

Spend roughly ten hours per phase across one or two services to build momentum, then scale.

• 10 discovery checks (Day 1–2): target frameworks, SDK pinning in CI, NuGet pre‑release packages, ASP.NET hosting model, Kestrel configuration, auth/Identity version, EF provider versions, database compatibility level, container base images, and observability exporters.
• 10 focused code updates (Day 3–7): bump TFM to net10.0, update SDK and toolchain, replace preview packages, adopt passkeys on one sign‑in path, add one SSE endpoint for a safe stream (e.g., notifications), align validation with IProblemDetailsService, enable new auth metrics, verify redirects for APIs, test JSON type mapping strategy, and update Dockerfiles to current base images.
• 10 deployment tasks (Day 8–10): canary slot with synthetic traffic, config freeze and feature flags, database migrations dry run and backout plan, SLA/SLO dashboards updated, load test, chaos test a rollout abort, security scan (including the latest Kestrel/runtime patches), blue/green cutover, incident playbook link, and post‑deployment verification checklist.

Capture the wins and rough spots, then repeat for the rest of your services. If you need a more structured 30‑day cadence, use our detailed guidance in the .NET 10 LTS 30‑day playbook and the ops‑oriented production upgrade guide.

Performance and cost: where .NET 10 LTS saves you money

Two practical savings show up fast:

• Lower memory pressure. Automatic eviction in memory pools and tighter runtime allocations cut peak RSS for long‑running apps. In Kubernetes, that often means bumping pod density or avoiding a class of OOMs you’ve been firefighting.
• NativeAOT and container polish. Ahead‑of‑time compilation keeps getting better. Small tools and services—especially job workers and gateways—start faster and use less memory, which translates to cheaper warm‑ups and fewer cold‑start surprises.

Is it dramatic across the board? No. But for APIs under bursty load or services you scale to zero, the combination is a quiet win.

People also ask

Do passkeys require Blazor?

No. The Blazor template makes passkeys turnkey, but passkey support lives in ASP.NET Core Identity. You can wire it into MVC or minimal APIs with the right Identity schema and UI.

Will EF Core 10 force database changes?

It depends on your provider and compatibility level. On Azure SQL and SQL Server 2025, adopting the native JSON type can generate migrations. Plan the switch explicitly, and test indexing strategies if you enable the new JSON index.

Is SSE a replacement for SignalR?

Not for bidirectional chat or collaborative editing. Use SSE for one‑way, low‑overhead streams: logs, progress, and live notifications. Keep SignalR (WebSockets) when clients must send frequent events upstream.

What to do next (this week)

• Decide your target: pick one customer‑facing API and one UI app to move first to .NET 10 LTS.
• Prove value fast: add passkey sign‑in for a subset of users and an SSE endpoint for a dashboard. Measure login success rate and time‑to‑first‑update.
• Close security gaps: verify you’re on patched Kestrel/runtime builds; ensure API auth returns 401/403, not redirects.
• Plan data shape: if you’re on Azure SQL or SQL Server 2025, decide when to introduce the native JSON type and indexes; review EF Core 10 migrations.
• Book your rollout window: line up a canary release and load test; assign clear owners for the migration and backout plan.

If you want a partner to own the risk and accelerate the timeline, our modernization services include a fixed‑scope upgrade track for .NET 10 LTS with hard deadlines, and our team can showcase relevant case studies from the portfolio. Have questions on scope or cost? Reach out via contacts and we’ll map a path that fits your release calendar.

Zooming out

Every LTS tempts teams to “wait for the next one.” This time, .NET 10 LTS earns the move: it locks in a security‑and‑observability uplift, gives you passwordless sign‑in without extra vendors, simplifies one‑way streaming, and lines your data tier up for AI features you’re likely to explore in 2026. Upgrade deliberately, not fearfully. Start small, ship a canary, watch the metrics, then finish the job.

And if your org is juggling multiple platform changes—frameworks, build pipelines, and front‑end migrations—we’ve written deeply on those, too. The caching and proxy patterns we covered in our Next.js 16 caching guide apply cleanly to ASP.NET Core reverse‑proxy setups, and the CI cautions in our GitHub Actions hardening guide still save teams from nasty supply‑chain surprises.