## TL;DR

XCUITest snapshots the accessibility hierarchy; queries run against a stale snapshot after UI changes. Re-query after transitions, wait for existence, and keep queries simple.

## Error

```text
Failed to get matching snapshot: No matches found for "loginButton"
```

## Steps

1. Add `waitForExistence(timeout:)` before the query. Expected: the UI settles first.
2. Re-fetch the element after every navigation or sheet dismissal; never reuse queries across transitions. Expected: fresh snapshots.
3. Simplify the query: fewer predicates, stable identifiers. Expected: less to go stale.
4. Check the hierarchy with `debugDescription` printout. Expected: you see what actually exists.
5. Re-run. Expected: green.

## When to use

- `failed to get matching snapshot` in XCUITest.
- After screen transitions.

## When not to use

- Appium XCUITest driver issues (different layer).
- Launch failures.

## Tool compatibility

- XCUITest; Xcode 14/15.

## Variant phrasings

### XCUITest no matches found

The short form; re-query after transitions.

### XCUITest stale query

The mechanism; snapshots go stale.

## Why it happens

XCUITest resolves queries against a captured hierarchy snapshot. UI changes invalidate it, and old query objects do not refresh.

## Edge cases

- `firstMatch` is faster but riskier; use it only for unique elements.
- Animations delay snapshot updates; wait for them.
- System alerts interrupt the hierarchy; handle them explicitly.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_1FEwqoxQLeA26SdWQ1mNng