Revit Addin Debugging

Revit Add-in Debugging

The Nice3point.Revit.Sdk makes the IDE's start-debugging action launch Revit and attach the debugger, without a launchSettings.json. Deploy the add-in first (revit-addin-publishing); the launched Revit loads the deployed build.

When to use

• Setting up a project where a debug session starts the right Revit version and breaks in the 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

<LaunchRevit>true</LaunchRevit>

The SDK sets StartAction=Program, StartProgram to C:\Program Files\Autodesk\Revit $(RevitVersion)\Revit.exe, and StartArguments=/language ENG; the IDE reads them, starts Revit, and attaches 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

<StartProgram>D:\Autodesk\Revit $(RevitVersion)\Revit.exe</StartProgram>
<StartArguments>/language CHS</StartArguments>

Set these when Revit is installed off the default path, or when forcing a language or opening a model on start.

Step 3: Keep Hot Reload working

Repacking (IsRepackable) merges dependencies as a post-build step that rewrites the output assembly; it defeats Hot Reload and slows the edit–run loop. For local debugging on Revit 2027+, leave IsRepackable off and rely on manifest-level isolation (revit-dependency-isolation); reserve repacking for release builds on pre-2027 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