Article · Revit API

.NET 8 support ends November 2026: what it means for your Revit add-ins

Your add-ins won't stop working on the day. But the runtime under Autodesk® Revit® 2025 and 2026 software is moving to .NET 10, Revit 2027 changed where add-ins install, and the safe path depends on exactly which update each machine runs.

By Shreyansh Shende, Founder, SS Technologies · October 2026 · About 6 minutes

The short version

  • Microsoft ends support for .NET 8 in November 2026. Revit 2025 and 2026 were built on .NET 8.
  • Autodesk says Revit 2025.5, 2026.5 and all later releases use .NET 10. Add-ins built for .NET 8 are expected to load there, but it isn't guaranteed.
  • An add-in built for .NET 10 won't load in a Revit version that still runs .NET 8. You can't simply retarget everything.
  • Revit 2027 runs on .NET 10, and all-user add-ins now install to Program Files.
  • Test every add-in on each Revit version, and each update, that your team runs. Start with add-ins that have windows or ship their own libraries.

What actually ends in November 2026

.NET is the Microsoft framework that Revit add-ins run on. Revit 2025 moved from .NET Framework 4.8 to .NET 8, and the Revit 2025 API notes said add-ins "will need to be rebuilt on .NET 8" (Revit API Docs, 2025). Revit 2026 stayed on .NET 8.

Microsoft ends support for .NET 8 in November 2026, as noted in the Revit API forum thread on the move to .NET 10 (Revit API forum). After that, Microsoft stops shipping security updates for it. Check Microsoft's .NET support policy for the exact date.

Nothing switches off on that date. Revit doesn't stop loading your add-ins, and the runtime keeps working. What changes is that the runtime under Revit 2025.0–.4 and 2026.0–.4 is no longer patched. Your IT or security team may start asking about it, and may want to roll out the Revit updates that move to .NET 10.

Autodesk's answer: .NET 10 in the .5 updates

On May 13, 2026, an Autodesk staff member confirmed on the Revit API forum that "Revit 2025.5, Revit 2026.5, and all later releases will use .NET 10" (Revit API forum). That's a runtime change in the middle of a release's life, delivered as an update rather than a new version. Because the source is a forum reply rather than formal documentation, check Autodesk's release notes for the update you install.

Three things follow from it, according to the same thread:

  • Most .NET 8 add-ins are expected to load on .NET 10. Expected, not guaranteed. Developers in the thread report problems with WPF, the framework many add-in windows are built with.
  • A .NET 10 build won't load on .NET 8. If half your office runs 2026.4 and half runs 2026.5, a .NET 10 build breaks for the first half.
  • So for Revit 2025 and 2026, keep shipping a .NET 8 build. Test it on both runtimes until every machine is on the .5 update or later.

Revit 2027: .NET 10 and a new install folder

Revit 2027 runs on .NET 10 (Autodesk Developer Blog, April 2026). Autodesk's notes on the 2027 SDK list changes that affect anyone who owns add-ins:

  • All-user add-ins moved from the ProgramData folder to C:\Program Files\Autodesk\Revit\Addins\2027. Program Files is a protected folder, so installs usually need administrator rights, and deployment scripts that copy files into ProgramData need updating.
  • Some APIs were removed. Code that compiled against Revit 2026 may not compile against 2027.
  • Manifest changes, including add-in isolation settings and how add-ins declare the libraries they depend on. Read Autodesk's notes before you rebuild.
  • New APIs, such as rule-based numbering schemas for any element, which may replace custom numbering code you maintain today.

What we ship for each Revit version

Sources: Revit API forum, Autodesk staff reply, May 2026; Autodesk Developer Blog, April 2026.
Revit versionRuntimeWhat we ship
2024 (2023 on request).NET Framework 4.8net48 build
2025.0–.4 and 2026.0–.4.NET 8.NET 8 build
2025.5+ and 2026.5+.NET 10 runtimeSame .NET 8 build, which Autodesk expects to load but doesn't guarantee, so we test on both
2027.NET 10.NET 10 build, installed to Program Files

What tends to break

Windows and dialogs (WPF)

Developers in the forum thread report WPF problems on the .NET 10 runtime. Any add-in with its own window needs a real click-through on 2025.5 or 2026.5: open every window, fill every grid, sort every list, and check styles and any third-party controls. Commands without a window need testing too.

Libraries you ship with the add-in

Many add-ins carry extra DLLs: a JSON library, an Excel reader, a database driver, logging. Each one has to support the runtime it loads into. Two add-ins that bring different versions of the same library can also clash inside one Revit session. Revit 2026 added optional isolation settings in the add-in manifest (UseRevitContext, ContextName) to help with this (Revit API Docs, 2026). Test with the other add-ins your team actually runs installed, not on a clean machine.

Older .NET features

Code carried over from .NET Framework days may lean on features that later .NET versions marked obsolete or removed. An add-in can build and load on .NET 8 and still fail on .NET 10 the first time it reaches that code. Read your compiler warnings, because they're the first to-do list, and test the commands people use least, not only the main ones.

Installers and deployment scripts

Hard-coded paths, version folders and the ProgramData location all need a look for 2027. So does any script that assumes users can install add-ins without administrator rights.

Scripts that are .NET underneath

Dynamo packages with compiled nodes and pyRevit both run on the same runtime. Test the current pyRevit release on your exact Revit version before relying on it on .NET 10 versions (pyRevit releases). Dynamo also changed its Python engine; see our Dynamo, pyRevit and C# comparison.

A practical migration checklist

  1. List every add-in. Include in-house tools, purchased add-ins, Dynamo packages with compiled nodes and pyRevit extensions. Note who holds the source code for each one.
  2. Record the exact Revit update on each machine. 2026.4 and 2026.5 now behave differently.
  3. Find the source code. If no one has it, decide early whether to ask the original vendor or plan a rebuild.
  4. Build every target from one project: net48 for 2024, net8.0-windows for 2025 and 2026, and net10.0-windows for 2027, each against that year's Revit API.
  5. Audit bundled libraries. Update or replace any that don't support .NET 8 and .NET 10.
  6. Compile against the Revit 2027 SDK. Fix removed APIs, then work through the warnings.
  7. Update manifests and installers. Install 2027 all-user add-ins to Program Files, and add isolation settings where libraries clash.
  8. Test on a matrix. Each Revit version, both runtimes for 2025 and 2026, a sample model and a copy of a real one, with your other add-ins loaded. Open every window.
  9. Roll out to a small group first, and keep the previous installer ready in case you need to roll back.
  10. Write down what changed. Autodesk releases a new Revit version every year, and good notes make the next upgrade faster.

If you only do three things this month

  • Find out which machines are on a .5 update, and which IT plans to update next.
  • Open every add-in window on a machine running 2025.5 or 2026.5.
  • Don't ship a .NET 10 build to Revit 2025 or 2026 users until all of them are on .5 or later.

This article reflects what Autodesk and Microsoft had published as of October 2026. Check the current Revit SDK notes and release notes before you rebuild, because details can change with each update.

Sources

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