DYN-10493: Fix crash in Getting Started guided tour#17111
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jasonstratton merged 1 commit intoMay 19, 2026
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… step 2 `HighlightPort` passes the result of `ContainerFromItem` through `ChildOfType<Grid>` to `CreateRectangle`. `ContainerFromItem` can return null when the ItemsControl hasn't generated containers yet — a timing race exposed by PR DynamoDS#16883 (DYN-7760) which added synchronous WebView2 extension-closing before tour startup. The null reached `NameScope.SetNameScope` and threw `ArgumentNullException("dependencyObject")`. Guard: if `mainGrid` is null, return early and skip the port highlight rather than crash. The tour continues without the visual effect. Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>
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See the ticket for this pull request: https://jira.autodesk.com/browse/DYN-10493
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Pull request overview
Fixes a guided tour startup crash in Dynamo’s Learning tab by preventing HighlightPort from passing a null visual container into the highlight-rectangle creation path when WPF hasn’t generated the port’s item container yet.
Changes:
- Add a null guard in
GuidesValidationMethods.HighlightPortto skip port highlighting when the port container/grid isn’t available yet, avoiding anArgumentNullExceptionduring tour initialization.
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Purpose
Fixes DYN-10493: Dynamo crashes when clicking "Start Tour" on the Getting Started guided tour (Learning tab). The crash occurs on the transition from the Welcome popup to step 2 ("nodes").
Root cause:
GuidesValidationMethods.HighlightPortcallsItemContainerGenerator.ContainerFromItemto locate the WPF container for a port, then passes the result toCreateRectangle.ContainerFromItemcan returnnullwhen theItemsControlhasn't generated containers yet. This is a timing race exposed by PR #16883 (DYN-7760, Feb 17 2026), which added synchronous WebView2 extension-closing before tour startup — shifting the dispatcher queue state enough to delay container generation past the point whereHighlightPortreads it. The resultingnullreachedNameScope.SetNameScopeinsideCreateRectangle, which throwsArgumentNullException("dependencyObject").Key changes:
mainGridinHighlightPort(GuidesValidationMethods.cs) — skips the port highlight rather than crashing if the container isn't ready. The tour continues without the visual effect.Regression introduced in: PR #16883 (DYN-7760, Feb 17 2026)
Not reproducible in: 4.0.2 and older
Fix targets:
master, cherry-pick to4.1.1Full investigation: DYN-10493 DynaNote (Autodesk internal)
Declarations
Release Notes
Fixed a crash that occurred when clicking "Start Tour" on the Getting Started guided tour (Learning tab).
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