Revit Addin Debugging

Revit Add-in Debugging

The Nice3point.Revit.Sdk makes the IDE's start-debugging action (F5 in Visual Studio, the Debug run in Rider) launch Revit and attach the debugger, driven by a few MSBuild properties — there is no launchSettings.json. Deploy the add-in first (revit-addin-publishing) so the launched Revit loads the build you are debugging.

When to use

• Setting up a project so a debug session starts the right Revit version and breaks in your add-in.
• Pointing the launcher at a non-default Revit install or start arguments.
• Keeping iterative debugging and Hot Reload responsive.

When not to use

• The build never needs to run under a debugger — plain DeployAddin copying is enough (revit-addin-publishing).

Workflow

Step 1: Enable launch

true

The SDK sets StartAction=Program, StartProgram to C:\Program Files\Autodesk\Revit $(RevitVersion)\Revit.exe, and StartArguments=/language ENG, which the IDE reads to start Revit and attach the debugger. Enable it in the manifest-owning project alongside DeployAddin; each build deploys before launch.

Step 2: Override the target when the defaults are wrong

D:\Autodesk\Revit $(RevitVersion)\Revit.exe
/language CHS

Set these when Revit is installed off the default path, or to force a language or open a model on start.

Step 3: Keep Hot Reload working

Repacking (IsRepackable) merges dependencies as a post-build step that rewrites the output assembly, which defeats Hot Reload and slows the edit–run loop. For local debugging on Revit 2026+, leave IsRepackable off and rely on manifest-level isolation instead (revit-dependency-isolation); reserve repacking for release builds on pre-2026 versions.

Step 4: Verify

Set a breakpoint in a command, start a debug session, and confirm the matching Revit launches, loads the add-in, and stops at the breakpoint.

Validation

• [ ] LaunchRevit is enabled in the manifest-owning project, alongside DeployAddin.
• [ ] StartProgram/StartArguments are overridden only when the defaults do not fit.
• [ ] IsRepackable is off for debug builds; isolation covers dependency conflicts.

Common Pitfalls

| Pitfall | Correct approach | |-----------------------------------------------|------------------------------------------------------------------------------| | Looking for a launchSettings.json | The SDK drives launch through LaunchRevit/StartProgram/StartArguments. | | A debug session starts Revit but the add-in is stale | Enable DeployAddin so the build deploys before launch. | | Hot Reload does nothing while repacking is on | Disable IsRepackable for debug; isolate dependencies via the manifest. | | The wrong Revit year launches | StartProgram uses $(RevitVersion); select the matching configuration. |

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: Nice3point
• Source: Nice3point/revit-skills
• License: MIT

Install and usage instructions live in the source repository linked above.