apache/druid · error · IllegalStateException

Got a [ ] which isn't a

Error message

Got a [%s] which isn't a %s

What it means

TimeseriesQueryRunnerFactory's runner only accepts TimeseriesQuery instances. run() type-checks the incoming QueryPlus payload and throws ISE if some other query class reaches the timeseries runner — an internal dispatch/wiring bug.

Solutions

1. Verify the query's JSON "query" type is "timeseries" and not altered in transit
2. Check extension versions: all Druid components must run the same version (no mixed classpath)
3. Ensure QueryRunnerFactory registrations map the correct query class to TimeseriesQueryRunnerFactory
4. Capture the full failing query JSON and validate it deserializes to TimeseriesQuery

Example fix

// before
QueryRunner<Row> r = factoryMap.get("topn").createRunner(segment); // wired wrong
// after
QueryRunner<Result<TimeseriesResultValue>> r = factoryMap.get("timeseries").createRunner(segment);

if (!(queryPlus.getQuery() instanceof TimeseriesQuery)) { throw new IllegalArgumentException("wrong runner for query type " + queryPlus.getQuery().getClass()); }

static boolean isTimeseries(Query<?> q) { return q instanceof TimeseriesQuery; }

try { return runner.run(queryPlus, ctx); }
catch (IllegalStateException e) { if (e.getMessage().startsWith("Got a [")) { throw new QueryInterruptedException(e); } throw e; }

When it happens

Trigger: A QueryPlus carrying a non-TimeseriesQuery (e.g. TopNQuery, GroupByQuery) is routed to the timeseries query runner factory, typically due to custom QueryToolChest/wiring, incorrect query type registration, or broken deserialization of query type fields.

Common situations: Custom extensions registering query runners with the wrong type mapping, forwarding queries between clusters with modified 'query/type' fields, classpath mixing Druid versions where query types changed package/name.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

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• Cannot call makeDimensionSelector on field of type
• Cannot cast [ ] to [ ] (Types.InvalidCastException from…

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/d2f9bf1da5f4a13a. Report an issue: GitHub.

Appendix: source

Thrown at processing/src/main/java/org/apache/druid/query/timeseries/TimeseriesQueryRunnerFactory.java:109

        TimeseriesQueryEngine engine,
        CursorFactory cursorFactory,
        @Nullable TimeBoundaryInspector timeBoundaryInspector
    )
    {
      this.engine = engine;
      this.cursorFactory = cursorFactory;
      this.timeBoundaryInspector = timeBoundaryInspector;
    }

    @Override
    public Sequence<Result<TimeseriesResultValue>> run(
        QueryPlus<Result<TimeseriesResultValue>> queryPlus,
        ResponseContext responseContext
    )
    {
      Query<Result<TimeseriesResultValue>> input = queryPlus.getQuery();
      if (!(input instanceof TimeseriesQuery)) {
        throw new ISE("Got a [%s] which isn't a %s", input.getClass(), TimeseriesQuery.class);
      }

      return engine.process(
          (TimeseriesQuery) input,
          cursorFactory,
          timeBoundaryInspector,
          (TimeseriesQueryMetrics) queryPlus.getQueryMetrics()
      );
    }
  }
}

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