LAZY_ASSET_UNMAPPED
lazy() component's client assets could not be resolved for the page (dev).
What you saw
- Kind:
ssr - Severity:
warn(code that works but is structurally wrong or expensive)
The console report opens with [LAZY_ASSET_UNMAPPED] and the message, then an in line naming the owners that enclose the subject, root first, and an at line with the source location when the code was compiled with one.
In a captured artifact the same finding is an event with code: "LAZY_ASSET_UNMAPPED", ownerPath, and loc.
Diagnostics explains each line.
Why it fires
A lazy() component's client chunk could not be resolved for the page (data.reason: the resolver threw, or the module has no $$moduleUrl), so it is not preloaded and loads late during hydration.
The server runtime reports on the same channel, with the same in <App> › <Page> line.
Two groups.
Findings (SSR_RENDER_ERROR_CONTAINED, SSR_SUBTREE_ABANDONED, SSR_STREAM_ABANDONED, LATE_HEADER_WRITE, DYNAMIC_ASYNC_COMPONENT, SERVER_ERROR_SANITIZED, FRAME_MARKER_CORRUPTED) are facts about a render that exist in observe builds too — an APM sees them in production; in dev they print.
Checks (the rest, SSR_BOUNDARY_WATERFALL and SSR_CLIENT_CONTENT_MASKED included) are dev-only guidance.
A captured artifact from a server render carries both.
How to fix it
This is bundler-plugin configuration — the plugin injects $$moduleUrl and provides the resolver; check the module is under its scope.
In tests
captureArtifact from @solidjs/diagnostics runs a scenario with the diagnostics channel open and returns the events it saw.
expectNoDiagnostics(artifact) fails while LAZY_ASSET_UNMAPPED is among them, with the events as evidence; after the fix, the code is gone from artifact.diagnostics.
Check for regressions in tests shows the loop and the Vitest matcher form.
Learn more
- Diagnostics: every code, with its kind, severity, and trigger.
- Debugging reactivity: how to read a report and what each group of codes points at.