cachedSerializedGroupMappingMap is not available from the…

Error message

cachedSerializedGroupMappingMap is not available from the coordinator, skipping fetch of group mappings for now.

What it means

CoordinatorPollingBasicAuthorizerCacheManager.tryFetchGroupMappingMapsFromCoordinator() polls the coordinator's group-mapping cache endpoint. A 404 means the endpoint (introduced in Druid 0.17.0) does not exist on the coordinator, so the fetch is skipped with this warning and null is returned. This is a deliberate backwards-compatibility path for rolling upgrades from pre-0.17.0 coordinators.

Solutions

Finish the rolling upgrade so all coordinators run 0.17.0+
Verify the request is hitting a coordinator process of the correct version (check druid.coordinator config and service discovery)
If upgrades are intentionally mixed, this warning is expected and safe to ignore temporarily
Ensure the basic-security extension version is consistent across the cluster

Defensive patterns

Strategy: fallback

Validate before calling

// check coordinator version capability before fetching
// GET /status on the coordinator and verify version >= 0.17.0

Try / catch

if (response.getStatus() == 404) {
  // expected during rolling upgrade; fall back to local cached group mappings
  return previousCachedMap;
}

Prevention

Complete rolling upgrades promptly so all coordinators are 0.17.0+
Pin basic-security extension versions consistently cluster-wide
Route group-mapping fetches to the current coordinator leader
Treat this warning as benign during mixed-version windows

When it happens

Trigger: Hitting GET coordinator/groupMappings cached endpoint on a coordinator older than 0.17.0, which lacks the endpoint and returns HTTP 404.

Common situations: Rolling upgrade: 0.17.0+ services running against an older coordinator; misrouted request to a non-coordinator service; stale reverse-proxy or load balancer pointing at an old coordinator.

Related errors

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/19bdc8ff670ce375. Report an issue: GitHub.

Appendix: source

Thrown at extensions-core/druid-basic-security/src/main/java/org/apache/druid/security/basic/authorization/db/cache/CoordinatorPollingBasicAuthorizerCacheManager.java:439

      String prefix
  ) throws Exception
  {
    RequestBuilder req = new RequestBuilder(
        HttpMethod.GET,
        StringUtils.format("/druid-ext/basic-security/authorization/db/%s/cachedSerializedGroupMappingMap", prefix)
    );
    BytesFullResponseHolder responseHolder = coordinatorClient.request(
        req,
        new BytesFullResponseHandler()
    );

    final HttpResponseStatus status = responseHolder.getStatus();

    // cachedSerializedGroupMappingMap is a new endpoint introduced in Druid 0.17.0. For backwards compatibility, if we
    // get a 404 from the coordinator we stop retrying. This can happen during a rolling upgrade when a process
    // running 0.17.0+ tries to access this endpoint on an older coordinator.
    if (HttpResponseStatus.NOT_FOUND.equals(status)) {
      LOG.warn("cachedSerializedGroupMappingMap is not available from the coordinator, skipping fetch of group mappings for now.");
      return null;
    }

    if (!HttpResponseStatus.OK.equals(status)) {
      LOG.warn("Got an unexpected response status[%s] when loading group mappings.", status);
    }

    byte[] groupRoleMapBytes = responseHolder.getContent();

    GroupMappingAndRoleMap groupMappingAndRoleMap = objectMapper.readValue(
        groupRoleMapBytes,
        BasicAuthUtils.AUTHORIZER_GROUP_MAPPING_AND_ROLE_MAP_TYPE_REFERENCE
    );
    if (groupMappingAndRoleMap != null && commonCacheConfig.getCacheDirectory() != null) {
      writeGroupMappingMapToDisk(prefix, groupRoleMapBytes);
    }
    return groupMappingAndRoleMap;
  }

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