# Playwright Trace Viewer Won't Open — No Trace, Blank Viewer, or Invalid Zip

Canonical: https://commareports.com/fix/playwright-trace-viewer-not-opening
Published: 2026-11-05

> The Playwright trace viewer shows nothing, says it must be loaded over http(s), or rejects the zip. The five causes — no trace recorded, file://, the CI double zip, version skew, blocked service workers — and the fix for each.

# Playwright trace viewer won't open

You click **Trace** on a failing test and get nothing, a blank pane, an
error about the protocol, or a complaint that the file is not a valid
trace. There are five causes, and each has a recognisable symptom.

| Symptom                                                    | Cause                                      |
| ---------------------------------------------------------- | ------------------------------------------ |
| No **Trace** link on the failing test at all               | No trace was recorded                      |
| Viewer says it must be loaded over `http://` or `https://` | Report or viewer opened from `file://`     |
| "Not a valid trace" / nothing loads from a CI download     | You opened the artifact zip, not the trace |
| Error mentioning a newer Playwright version                | Viewer older than the trace format         |
| Viewer hangs on a hosted report or in a private window     | Service worker can't register              |

## 1. No trace was recorded

This is the most common one, and it is a config default. The config
that `npm init playwright` generates contains:

```ts
// playwright.config.ts
retries: process.env.CI ? 2 : 0,
use: {
  trace: "on-first-retry",
},
```

`on-first-retry` records a trace **only on the first retry**. Locally,
`retries` is 0, so a failing test never retries and never records one.
On CI it does — but only for tests that failed once.

For a one-off local run:

```bash
npx playwright test --trace on
```

To keep a trace for every failure without paying for passing tests:

```ts
use: {
  trace: "retain-on-failure",
},
```

| `trace` mode        | Records          | Keeps             |
| ------------------- | ---------------- | ----------------- |
| `off`               | nothing          | —                 |
| `on`                | every test       | everything        |
| `retain-on-failure` | every test       | failed tests only |
| `on-first-retry`    | first retry only | that retry        |
| `on-all-retries`    | every retry      | every retry       |

`retain-on-failure` records everything and deletes the passing ones, so
it costs run time but not disk. On a large suite, `on-first-retry` with
`retries` above 0 on CI is still the cheapest setup that catches flakes
— just know it is the reason your local run has no trace.

## 2. Opened from `file://`

The trace viewer runs its loader in a **service worker**, and browsers
do not register service workers for `file://` pages. Double-clicking
`playwright-report/index.html` gets you the test list (that part is
inlined), but clicking a trace hits an error saying the viewer must be
loaded over `http://` or `https://`.

Serve it instead:

```bash
npx playwright show-report                 # serves ./playwright-report
npx playwright show-trace path/to/trace.zip  # opens one trace directly
```

Or open [trace.playwright.dev](https://trace.playwright.dev) and drop
the zip on it. It is a static build of the same viewer; the zip is read
inside your browser, not uploaded.

The same `file://` restriction is why the whole report can come up
empty on larger runs — see
[Playwright report is blank](/fix/playwright-report-blank).

## 3. The CI double zip

GitHub Actions hands every artifact back as a **zip of what you
uploaded**. Upload `trace.zip` and the download is a zip containing
`trace.zip`. Upload `playwright-report/` and the traces are the `.zip`
files inside its `data/` folder, inside the artifact zip.

Pass the outer archive to `show-trace` or trace.playwright.dev and it
fails — it is a zip, just not a trace. Unzip the artifact first:

```bash
unzip playwright-report.zip -d report
ls report/data/*.zip            # these are the traces
npx playwright show-trace report/data/<hash>.zip
```

The rest of what goes wrong with artifacts is in
[GitHub Actions artifact HTML won't open](/fix/github-actions-artifact-html-not-viewable).

## 4. Version skew

The trace format changes between Playwright releases. A trace recorded
by a newer Playwright than the one running `show-trace` can fail with
an error about the newer version. Run the viewer at the version that
recorded it:

```bash
npx playwright@1.56.0 show-trace trace.zip   # match the CI version
```

trace.playwright.dev tracks the latest release, so it opens traces from
older versions too — the quickest fallback when the local install is
behind CI.

## 5. The service worker can't register

Even over HTTPS, the viewer needs a service worker, and some contexts
refuse one:

- **Sandboxed iframes without `allow-same-origin`.** The page gets an
  opaque origin, and an opaque origin cannot register a service
  worker. This is how most report hosts that run untrusted HTML work —
  Comma included ([why](/glossary/iframe-sandbox)).
- **Private windows and hardened profiles** that disable service
  workers.
- **Remote URLs passed with `?trace=`.** trace.playwright.dev can load
  `https://trace.playwright.dev/?trace=https://…/trace.zip`, but the
  host must send `Access-Control-Allow-Origin`. A presigned S3 URL
  without a bucket CORS rule fails here.

The fix is to open the trace somewhere that has a normal origin: the
local `show-trace`, or trace.playwright.dev with the file dropped in.

## Where Comma fits

Comma shows the Playwright HTML report — test list, steps, errors —
with scripts running, and lets reviewers comment on the failing test
itself. It does **not** run the trace viewer: report HTML renders in a
sandboxed iframe, which is the condition in cause 5. Attach the trace
zips as assets so they travel with the report; the reviewer downloads
the one they need and opens it in `show-trace` or trace.playwright.dev,
then comes back to the thread with what they found.

One caution before you publish traces anywhere: a trace contains DOM
snapshots, network requests and responses, cookies and typed input from
the run. If the suite logs in with real credentials, the trace has
them. Use test accounts, and share the report with people, not with a
public link. More in [Playwright trace](/glossary/playwright-trace).

## Try it

Comma is free — unlimited reports, unlimited commenters, unlimited
revision history.

**[Publish a Playwright report →](https://commareports.com/)**

### Related

- [Playwright report is blank](/fix/playwright-report-blank)
- [Share a Playwright report](/share-playwright-report)
- [Playwright trace](/glossary/playwright-trace) · [Flaky test](/glossary/flaky-test)
- [Same-origin policy](/glossary/same-origin-policy) · [iframe sandbox](/glossary/iframe-sandbox)