**Found in version**
- Observed in 8.2.3, but might exist longer

**Steps to reproduce**
On a multi node cloud cluster (might also work on a local multi node cluster):
- Create a transform with a retention policy
- Update the transform and remove the retention policy

**Expected result**
- The retention policy is removed

**Actual result**
- This sometimes results in an error:
```
An error occurred calling the API endpoint to update transforms.
Bad Request: [illegal_argument_exception: [illegal_argument_exception] Reason: 
Unknown NamedWriteable [org.elasticsearch.xpack.core.transform.transforms.RetentionPolicyConfig][null_retention_policy]]:
Unknown NamedWriteable [org.elasticsearch.xpack.core.transform.transforms.RetentionPolicyConfig][null_retention_policy]
```

**Additional information**
- Quote from slack discussion with @benwtrent:
  > It wouldn’t happen if you hit a node that can execute the update immediately without serializing to a different node
x-pack/plugin/transform/qa/multi-node-tests/src/javaRestTest/java/org/elasticsearch/xpack/transform/integration/TransformIT.java
indexMoreDocs(timeStamp, user, indexName);
        waitUntilCheckpoint(config.getId(), 2L);
        
        assertThat(
            (Integer) XContentMapValues.extractValue("stats.documents_indexed", getTransformStats(config.getId())),
            greaterThan(docsIndexed)
        );
        
        assertThat(pagesProcessed, lessThan(1000));
        stopTransform(config.getId());
        deleteTransform(config.getId());
    }
    private void indexMoreDocs(long timestamp, long userId, String index) throws Exception {
        StringBuilder bulkBuilder = new StringBuilder();
        for (int i = 0; i < 25; i++) {
            bulkBuilder.append("""
                {"create":{"_index":"%s"}}
                """.formatted(index));
            int stars = (i + 20) % 5;
            long business = (i + 100) % 50;
            String source = """
                {"user_id":"user_%s","count":%s,"business_id":"business_%s","stars":%s,"timestamp":%s}
                """.formatted(userId, i, business, stars, timestamp);
            bulkBuilder.append(source);
        }
        bulkBuilder.append("\r\n");
        doBulk(bulkBuilder.toString(), true);
    }
}