The story router only knew the pre-v2 route names, so SidebarNav's RouterLink to the v2-prefixed 'v2-dashboard' threw 'No match for' and the Storybook error boundary replaced every AppSidebar story. Add 'v2-dashboard' to the story router's known names. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>