# HP9001: Hydration did not finish in time

> HP9001 (hydration-timeout) means React loaded but hydration did not finish before the timeout. Raise the timeout or find the Suspense boundary that hangs.

Source: https://hydration.jscrate.dev/docs/issues/hp9001
Last updated: 2026-09-18

HP9001 (`hydration-timeout`) means React loaded on the page, but hydration did
not complete before the timeout, so the page could not be compared. Usually a
Suspense boundary never resolves in the test environment, or the page is very
slow to hydrate. Find the boundary that hangs, or increase the hydration
timeout.

| | |
| --- | --- |
| Code | `HP9001` |
| Name | `hydration-timeout` |
| Default severity | Error |
| Group | Test run problems |
| What it means | React was on the page but hydration did not complete before the timeout. |

## What the HP9001 hydration timeout finding means

hydration-proof waits for React's hydration to finish before it takes its
snapshots. Once React is on the page, it waits up to `ready.hydrationTimeout`
(15 seconds by default), within the page's overall `ready.timeout` (30
seconds). When the time runs out, the finding says how many boundaries are
still waiting:

```text
Hydration did not finish: 2 Suspense or Activity boundaries are still dehydrated.
Hydration did not finish before the timeout.
```

It is an error: nothing after hydration could be checked on that page.

### The info variant

React hydrates some boundaries only when the user interacts with them. When
every pending boundary already has its content and the page has been quiet for
two seconds, hydration-proof stops waiting and reports HP9001 as info instead:

```text
React did not hydrate 1 Suspense boundary whose content had already arrived; React hydrates it on the first interaction.
```

The page is still tested; only those boundaries are not compared.

## Likely causes

- A Suspense boundary whose data never arrives in the test environment: an API
  that is not running, a request the test browser cannot reach, a promise that
  never resolves.
- A slow scenario: throttled network (`network: "slow-3g"`) or CPU (`cpu: 4`)
  with a large bundle.
- A script error that stops hydration part-way; look for
  [HP2007](https://hydration.jscrate.dev/docs/issues/hp2007) on the same page.

## How to fix it

Increase the hydration timeout, or check for Suspense boundaries that never
resolve in the test environment.

1. Open the route with `--headed` and watch which part stays in its fallback.
2. Make the data available to the test: start the API, seed it in
   `hooks.setup`, or answer the browser's requests with `mocks` in the
   scenario (see [scenarios](https://hydration.jscrate.dev/docs/scenarios)).
3. If the page is just slow, raise the limits. Keep `ready.timeout` above
   `ready.hydrationTimeout`, since it covers the whole page:

```ts title="hydration-proof.config.ts"
import { defineConfig } from "hydration-proof";

export default defineConfig({
  ready: { hydrationTimeout: 30_000, timeout: 60_000 },
});
```

A route object can set its own `ready` options, so one slow page does not slow
down the rest; see [routes](https://hydration.jscrate.dev/docs/routes).

## Related

- [HP9009: the page never became quiet](https://hydration.jscrate.dev/docs/issues/hp9009)
- [HP9008: React loaded but never mounted a root](https://hydration.jscrate.dev/docs/issues/hp9008)
- [HP2003: a Suspense boundary switched to client rendering](https://hydration.jscrate.dev/docs/issues/hp2003)
- [The ready options](https://hydration.jscrate.dev/docs/configuration)
- [Troubleshooting test runs](https://hydration.jscrate.dev/docs/troubleshooting)