.NET 10 LTS landed on November 11, 2025, with three years of support through November 2028 and a now‑standard two‑year window on odd‑year STS releases. That’s a strong incentive to get current before Q1 projects pile up. But here’s the thing: platform readiness isn’t uniform yet, especially across serverless and PaaS stacks. Let’s separate the marketing headlines from the engineering reality and map the fastest, safest path to adopt .NET 10 LTS in production. (devblogs.microsoft.com)
What’s actually new in .NET 10 LTS that matters for shipping teams
C# 14: small syntax, big ergonomics
C# 14 isn’t flashy for the sake of it; it’s a grab bag of sharp edges smoothed out. Extension members consolidate related extensions; null‑conditional assignment cleans up defensive code; implicit conversions around Span/ReadOnlySpan unlock leaner, allocation‑free paths the BCL already uses. Even if your team never writes a single extension member this quarter, libraries you depend on will—and you get the perf wins. (learn.microsoft.com)
EF Core 10: vector search goes mainstream
EF Core 10 is LTS and requires .NET 10. The headline for many products: first‑class support for the Azure SQL/SQL Server vector data type and VECTOR_DISTANCE(), meaning you can run hybrid relational + vector queries without duct‑taping another store into your stack. If your roadmap includes RAG or recommendations, this is the simplest path to get an MVP into production on your existing data tier. (learn.microsoft.com)
Microsoft’s data team has also been tuning the plumbing: binary vector transfers in Microsoft.Data.SqlClient significantly speed up reads and writes when you stop shipping JSON arrays for embeddings. If performance budgets are tight, that’s real money. (devblogs.microsoft.com)
Runtime and ASP.NET Core: quieter gains you’ll actually feel
Much of the raw throughput bump in .NET 10 comes from the runtime and BCL leaning into those Span improvements. For web APIs, that means less allocation churn and better inlining—incremental but compounding gains. If you’ve been patching around October’s high‑severity Kestrel issue, moving to the newest LTS and its security fixes keeps you off the treadmill of emergency patch sprints. (devblogs.microsoft.com)
Tooling: Visual Studio 2026 and day‑zero libraries
Visual Studio 2026 shipped the same day as .NET 10 (18.0), and 18.0.1 has already landed. Enterprise teams that standardize on the IDE can flip to a supported toolchain quickly. Major UI suites announced .NET 10 support at launch; that helps unblock front‑end teams dependent on those components. (learn.microsoft.com)
People also ask: should we upgrade to .NET 10 LTS now or wait?
If you’re on .NET 8 LTS, the support runway runs through November 10, 2026. If you’re on .NET 9 STS, you also have coverage to the same date after Microsoft extended STS to 24 months. Translation: most teams have breathing room. The decision turns on platform readiness and dependency risk, not the calendar. (dotnet.microsoft.com)
Platform readiness: what’s truly supported in late November 2025
Azure App Service (Web Apps)
App Service generally aligns with .NET’s support policy, but the exact runtime selector lags in the UI and CLI in the first weeks of a major release. If you’re deploying to Linux plans, verify what stacks are live in your region rather than assuming. Use az webapp list‑runtimes and set linuxFxVersion explicitly (syntax DOTNETCORE|x.x), or sidestep it by publishing self‑contained or containerized. This avoids the “works locally, fails on portal defaults” trap. (learn.microsoft.com)
Azure Functions
Functions 4.x remains the GA host. As of this week, docs reflect .NET 10 preview support in the Functions matrix, with GA typically trailing the core runtime. If your APIs depend on isolated Functions, keep them on .NET 8/9 or bring your own container until the Functions worker flips to .NET 10 GA. (learn.microsoft.com)
AWS Lambda
AWS’ managed .NET 10 runtime is slated for January 2026. If you’re eager, you can deploy .NET 10 via container images or Native AOT on an OS‑only runtime, but budget time for cold start profiling and layer updates. For most Lambda workloads, plan your move in Q1 once the managed runtime is out. (docs.aws.amazon.com)
CI/CD images and installers
Hosted build agents and Actions runners update on a cadence; don’t wait. Pin the SDK with the dotnet‑install script and channel 10.0 in your pipeline, then lift your container base images to 10.0 for release steps. This decouples your migration from image rollouts in hosted pools. Keep an eye on the official downloads page to match SDK/Runtime builds across agents and dev machines. (learn.microsoft.com)
What breaks, what wins: a pragmatic read
The good news: from net8.0 or net9.0, most web/API projects retarget and build. Your risk sits in three places: EF Core provider timing (e.g., MySQL/Postgres/Oracle drivers hitting EF10), Functions/Lambda runtime availability, and vendor SDKs that haven’t toggled their target frameworks. On the upside, teams adopting EF10 with Azure SQL vectors can delete an entire external vector store and its sync jobs—less surface area, fewer pagers. (learn.microsoft.com)
The 30‑60‑90 day .NET 10 LTS upgrade playbook
Days 0–30: prove it builds, prove it runs
• Create a branch for the retarget: update TargetFramework to net10.0 and set LangVersion to latest. • Pin SDK via dotnet‑install in CI and on dev boxes. • Update EF Core to 10.0.x and your core libraries; note that EF10 requires .NET 10. • Spin a staging environment; if you’re on App Service, deploy as self‑contained or containers to avoid portal runtime drift. • Flip a canary API in production behind a route or header and baseline p50/p95 latencies, allocations, and GC activity. (learn.microsoft.com)
Days 31–60: remove risk, raise the ceiling
• Enable C# 14 in a few hotspots: parsing, text processing, and tight loops that benefit from Span‑friendly APIs. • If you’re evaluating AI features, prototype vector search with EF10 + Azure SQL vectors (or SQL Server 2025) and measure read/write throughput using the updated SqlClient. • For serverless, prepare containerized builds so you can move when Functions/Lambda GA arrives. • Lock your container base to 10.0.0 for the holiday period; resume patch cadence in January. (devblogs.microsoft.com)
Days 61–90: production scale and governance
• Roll across services using a ring or traffic‑split rollout with automatic rollback. • Add a persistent “what changed” dashboard: SDK, runtime, EF, and driver versions, surfaced alongside SLOs. • Update playbooks for incident responders: include the October Kestrel advisory context and how the current LTS mitigates it. • Schedule a post‑go‑live patch window aligned with .NET’s Patch Tuesday cadence. (techradar.com)
People also ask: does Azure App Service fully support .NET 10 yet?
Support appears region‑by‑region and sometimes UI‑by‑UI. The reliable way to confirm is to query available runtimes via CLI, or to deploy self‑contained/containerized so you’re not dependent on the platform image switch. If Functions or extensions are involved, wait for the worker to advertise .NET 10 GA. (learn.microsoft.com)
People also ask: when will AWS Lambda support .NET 10?
AWS’ documentation lists January 2026 as the target month for the managed .NET 10 runtime. Until then, containers and OS‑only runtimes are your path—fine for advanced teams, but plan extra validation on cold starts and layers. (docs.aws.amazon.com)
A quick production checklist (use it today)
- TargetFramework = net10.0; set LangVersion = latest; ensure Visual Studio 2026 18.0+ on Windows machines. (learn.microsoft.com)
- Pin SDKs in CI with dotnet‑install --channel 10.0; avoid relying on hosted image updates. (learn.microsoft.com)
- Upgrade EF Core to 10.0.x and validate providers; if using Azure SQL vectors, switch to binary vector types via Microsoft.Data.SqlClient. (learn.microsoft.com)
- For App Service, prefer containerized/self‑contained until your region advertises the runtime; verify with az webapp list‑runtimes and correct linuxFxVersion syntax. (learn.microsoft.com)
- For Functions and Lambda, plan Q1 moves; containers as a bridge if needed. (learn.microsoft.com)
Zooming out: why move now if .NET 8 is supported until 2026?
You’re not forced to move, but you are rewarded. The STS policy change means future odd‑year releases won’t be a trap. EF10 plus native vectors in Azure SQL/SQL Server 2025 shrink your architecture. And C# 14’s Span‑friendly changes quietly cut CPU and allocations across hot paths. If you batch this with your usual Q1/Q2 dependency upgrades, you’ll ship fewer moving parts later in 2026. (devblogs.microsoft.com)
What to do next
• If you want a deeper, dates‑and‑risks brief, we wrote a field guide you can hand to leadership: .NET 10 LTS upgrade playbook. • Running on App Service? Read our take on runtime gaps and workarounds in App Service + .NET 10: what to fix now. • Planning a broader modernization cycle? Our services page outlines how we structure safe upgrades, and our argument for moving this quarter covers the business case. For a taste of how we run production upgrades under pressure, check our 12‑step CDN resilience playbook—same discipline, different layer.
FAQ for busy leads
Will our team need to rewrite code for C# 14?
No. You can adopt C# 14 incrementally. Start where Span/ReadOnlySpan helps, and let BCL/library updates do most of the heavy lifting. (devblogs.microsoft.com)
Is EF Core 10 mandatory?
If you’re moving to .NET 10, yes—EF10 is the compatible LTS line, and it unlocks vector support that EF9 can’t. Plan provider validation early. (learn.microsoft.com)
How long can we stay on .NET 8?
Through November 10, 2026, but remember: the longer you wait, the more libraries and tools assume net10.0 in their day‑to‑day testing. (dotnet.microsoft.com)
