Reference

What BugMojo can't capture

Understand the handful of things session replay can't reconstruct, why, and how to work around each one.

Applies toWhere:ExtensionWeb app

BugMojo captures a lot automatically, but session replay has real limits. Because replay reconstructs the DOM with rrweb instead of recording pixels, a few surfaces simply can't be rebuilt. This page lists exactly what those are, why, and what to do instead.

Cross-origin iframes

An iframe loaded from a different origin (a payment widget, an embedded map, a third-party chat) is sandboxed by the browser. For security reasons the extension can't read the DOM inside it, so replay shows the iframe's outline but not its live contents. Same-origin iframes usually record fine.

Canvas, WebGL, and video

A <canvas>, a WebGL scene, or a native <video> element paints pixels that never exist as DOM nodes. There's nothing for rrweb to serialize, so these areas appear blank or frozen in replay. The surrounding page still records normally, and console and network capture continue throughout.

Shadow DOM edge cases

Most web components with an open shadow root record correctly. The exceptions are closed shadow roots, which scripts can't inspect, and a small number of components that mutate their shadow tree in unusual ways. In those cases replay may miss changes inside the component even though the rest of the page is intact.

Workarounds

  1. Add an annotated screenshot to the report. Screenshots capture real pixels, so they show canvas, WebGL, video, and iframe content that replay can't reconstruct.

  2. Lean on the data that is captured: console logs, network requests with method, URL, status, and timing, and full device, OS, browser, and viewport metadata.

  3. In your description, note the exact moment and what you saw in the affected area. That gives a teammate or an AI agent the context replay is missing.

Common questions

Why is a section of my replay blank or grey?

It usually contains a cross-origin iframe, a canvas, a WebGL scene, or a video element. Those pixels can't be reconstructed from the DOM, so replay shows a placeholder. Add a screenshot to fill the gap.

Does BugMojo record video of my screen?

No. BugMojo reconstructs the DOM with rrweb rather than recording pixels. That makes replays tiny and privacy-safe, but it also means pixel-only surfaces like canvas and native video won't appear.

Can I still report a bug that lives in a canvas or iframe?

Yes. Use an annotated screenshot to show the visual, and lean on the console logs, network requests, and metadata BugMojo still captures around it.

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Updated Jul 10, 2026 · Still stuck? Contact support

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