flowable/flowable-engine · error · FlowableException

Decision has multiple results

Error message

Decision has multiple results

What it means

DmnDecisionRuleResult wraps a DMN decision's rule output rows. getSingleRuleResult() is only valid when the decision produced exactly one result; with more than one row it refuses to guess which to return and throws. Use getFirstRuleResult() or the full result list when multiple outcomes are expected.

Solutions

1. Call getFirstRuleResult() if any result is acceptable.
2. Iterate the full ruleResults list and handle each row.
3. Tighten decision table rules / set hit policy (e.g. UNIQUE or FIRST) so only one result is produced.
4. Check ruleResults.isEmpty()/size() before calling getSingleRuleResult().

Example fix

// before
Map<String, Object> result = ruleResult.getSingleRuleResult();
// after
Map<String, Object> result = ruleResult.getFirstRuleResult();

if (ruleResult != null && ruleResult.size() == 1) {
    Map<String, Object> single = ruleResult.getSingleRuleResult();
} else if (ruleResult != null && ruleResult.size() > 1) {
    // handle multi-result case first
}

boolean hasSingleResult(DmnDecisionRuleResult r) { return r != null && r.size() == 1; }

try { return ruleResult.getSingleRuleResult(); } catch (FlowableException e) { if ("Decision has multiple results".equals(e.getMessage())) return ruleResult.getFirstRuleResult(); throw e; }

When it happens

Trigger: Calling dmnDecisionService.executeDecision... then getSingleRuleResult() on a decision table whose rules matched multiple times (multiple output rows), or a decision whose expression produced several outputs.

Common situations: Multi-hit decision tables (hit policy not unique), rules with overlapping conditions so several rules fire, developers assuming single-result semantics.

Related errors

• more than one result
• more than one result in decision:
• Could not create conclusion result
• DMN decision with key
• DMN decision with key

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/3b292a07faea97b4. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-dmn-api/src/main/java/org/flowable/dmn/api/DmnDecisionRuleResult.java:56

        for (Map<String, Object> ruleOutputValues : ruleResults) {
            outputValues.add(ruleOutputValues.get(outputName));
        }
        return outputValues;
    }

    public Map<String, Object> getFirstRuleResult() {
        if (ruleResults.size() > 0) {
            return ruleResults.get(0);
        } else {
            return null;
        }
    }

    public Map<String, Object> getSingleRuleResult() {
        if (ruleResults.isEmpty()) {
            return null;
        } else if (ruleResults.size() > 1) {
            throw new FlowableException("Decision has multiple results");
        } else {
            return getFirstRuleResult();
        }
    }
}

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