**Affected version:** 7.12 - 7.17.7, 8.0-8.5
**Fixed in:** 7.17.7, 8.5.0

### Problem Description

A continuous transform can fail if a transform is searching at the same time as an ILM action occurs or in general anything that closes an index. This should not happen if transform is configured with a wildcard pattern for the source index, e.g. `filebeat-*`.

In a specific case an ILM policy temporarily closes the index due to the unfollow-the-follower action.

A typical log entry for this bugs contains something like this:

```
task encountered irrecoverable failure: org.elasticsearch.cluster.block.ClusterBlockException: index [ ... ] blocked by: [FORBIDDEN/4/index closed];
```

### Mitigation

A: Restart the transform. This can be automated by monitoring `_stats` and restarting the transform using `_stop?force=true` followed by `_start`.

B: Don't use the ILM unfollow action until a fix is available.

C: **Unreleased**: Starting with 8.5 set the transform to `unattended` mode via `settings`, this will let transform retry even for this failure class

### Solution

If the source of a transform is configured with a wildcard, transform should not treat an index closed exception as an irrecoverable failure.

### Backport

The fix needs to be backported to the `7.17` series.
x-pack/plugin/transform/src/test/java/org/elasticsearch/xpack/transform/transforms/TransformFailureHandlerTests.java
"painless"
                        )
                    ) }
            ),
            contextListener,
            settings
        );
        assertNoFailure(
            handler,
            new ElasticsearchStatusException("something really bad happened", RestStatus.INTERNAL_SERVER_ERROR),
            contextListener,
            settings
        );
        assertNoFailure(handler, new IllegalArgumentException("expected apples not oranges"), contextListener, settings);
        assertNoFailure(handler, new RuntimeException("the s*** hit the fan"), contextListener, settings);
        assertNoFailure(handler, new NullPointerException("NPE"), contextListener, settings);
    }
    private void assertNoFailure(
        TransformFailureHandler handler,
        Exception e,
        MockTransformContextListener mockTransformContextListener,
        SettingsConfig settings
    ) {
        handler.handleIndexerFailure(e, settings);
        assertFalse(mockTransformContextListener.getFailed());
        assertEquals(1, mockTransformContextListener.getFailureCountChangedCounter());
        mockTransformContextListener.reset();
    }
}