Upgrade from 3.x to 4

RevitDevTool 4 changes how it installs and updates, how .NET tests run, and how an AI client talks to a host. This page lists what to do when you move from 3.x to 4.0.0-beta.8 or later. For every change, see Release Notes.

What changes

Area	3.x	4
Installer	Inno Setup, with an uninstall entry in Windows Apps	RevitDevTool-Setup.exe from a daemon/v... release; no administrator rights
Add-in	One RevitDevTool.bundle for every host	RevitDevTool.bundle for Revit and AcadDevTool.bundle for the AutoCAD family; only the hosts you select
Daemon and MCP server	Inside the add-in bundle	%LOCALAPPDATA%\RevitDevTool\current\DevTools.Daemon.exe
Updates	Download and run a new installer	Updates tab in the Daemon window; the Daemon and the add-in update separately
Versions	One version for everything	Four products with their own versions: Daemon, add-in, RevitDevTool.TestAdapter, revitdevtool-pytest
MCP tools	list_host_instances, launch_host, open_model, read_file_info	list_processes, launch_host, read_file_info, code_mode
.NET tests	Not available	NUnit, TUnit, or MSTest through RevitDevTool.TestAdapter
pytest	revitdevtool_pytest from its own repository	revitdevtool-pytest 0.6.1, built from this repository

1. Remove 3.x

The 4 installer does not remove a 3.x install. Do it first, so the old Daemon and the old bundle do not stay behind.

1. Close Revit, AutoCAD, and every other Autodesk host.
2. Quit the old Daemon from the notification area, if it is running.
3. Open Windows Settings, Apps, Installed apps, find RevitDevTool, and choose Uninstall.
4. Check that %APPDATA%\Autodesk\ApplicationPlugins\RevitDevTool.bundle is gone. Delete the folder if it is still there.

2. Install 4

1. Download RevitDevTool-Setup.exe from the newest daemon/v... release on GitHub Releases and run it.
2. Open the Daemon window and go to the Updates tab.
3. Tick Include pre-releases while 4 is in beta.
4. Tick each host and version you use, then choose Update. Each row installs the add-in for that host and version.
5. Start the host. The panel title shows the installed version, for example DevTools 4.0.0-beta.8.

See Installation for the ribbon buttons and a first script.

3. Keep it up to date

• The Daemon and the add-in each follow a channel: stable, or prerelease when Include pre-releases is on.
• Check for updates looks for new versions. Install updates automatically installs them without asking.
• An add-in update for a host that is running waits until that host closes. The other hosts update right away.
• Restart the host after an add-in update, so it loads the new version.
• Releases of 4.0.0-beta.7 and earlier cannot read the new update channel. If you installed one of them, run RevitDevTool-Setup.exe once more.

4. Point your AI client at the new server

The MCP server is the Daemon itself. Replace the old command in your client's MCP configuration:

mcp.json

{
  "mcpServers": {
    "revitdevtool": {
      "type": "stdio",
      "command": "%LOCALAPPDATA%/RevitDevTool/current/DevTools.Daemon.exe",
      "args": ["--stdio"]
    }
  }
}

Tools that changed:

3.x	4
list_host_instances	list_processes
open_model	open_document, called inside the host through code_mode
Searching and calling host tools one by one	code_mode: the client writes one short C# program that searches, describes, invokes, and reads host capabilities

The full list is in MCP Protocol.

5. Reload your toolsets

• Load a .NET toolset from the MCP toggle in the panel with Load .NET Toolset, or a Python toolset folder (a *mcp.py entry file) with Load Python Toolset. An AI client can do the same with add_tools.
• A .NET toolset ships its own ModelContextProtocol package. Keep it copy-local and do not set ExcludeAssets="runtime"; the host does not lend its copy. A toolset built without it loads but cannot return results.
• Rebuild the toolset against the MCP SDK version in MCP .NET.

6. Update your tests

pytest

• Install revitdevtool-pytest 0.6.1 (see pytest).
• Renamed options:

Old option	New option
--host-launch	--force-launch
--host-launch-timeout	--launch-timeout
--host-timeout	--per-test-timeout

• The host pipe is now named DevTools_{Host}_{Version}_{PID}. Update --host-pipe if you pass it.
• IronPython tests: name the file test_*_ipy.py and write unittest test cases (see unittest).

.NET tests (new)

• Add the RevitDevTool.TestAdapter package, 0.3.0 or later, and pin NUnit, TUnit, or MSTest yourself. The add-in ships no test framework.
• The adapter needs the add-in 4.0.0-beta.8 or later and the .NET 10 runtime on the machine that runs dotnet test.
• If a project already uses an adapter from 0.0.1 to 0.2.0 with a 4 beta, move it to 0.3.0 and add the framework package it runs.
• Start with Testing Overview.

What stays the same

• Scripts keep their entry files and the shared state on sys.__devtool__.
• Settings and logs stay under %APPDATA%\RevitDevTool.
• Supported hosts: Revit, AutoCAD, Civil 3D, Plant 3D, and the AutoCAD verticals, 2022 to 2027.