flowable/flowable-engine · error · FlowableException

Query return " + results.size() + " results instead of max 1

Error message

Query return " + results.size() + " results instead of max 1

What it means

Result-shape guard in AbstractNativeQuery.executeSingleResult: singleResult() was called but the native query returned more than one row (count included in message); the caller must narrow the query or use list().

Solutions

1. Add a where-clause/limit so the native query returns exactly one row
2. Use list() instead of singleResult() when multiple rows are expected

Example fix

// before
Object r = managementService.createTableQuery()
    .sql("SELECT * FROM ACT_RU_EXECUTION WHERE PROC_INST_ID_ = #{pid}")
    .singleResult();
// after
Object r = managementService.createTableQuery()
    .sql("SELECT * FROM ACT_RU_EXECUTION WHERE PROC_INST_ID_ = #{pid} LIMIT 1")
    .singleResult();

// ensure uniqueness before singleResult()
List<Map<String,Object>> all = managementService.createTableQuery()
    .sql("SELECT * FROM ACT_RU_EXECUTION WHERE PROC_INST_ID_ = #{pid}").list();
if (all.size() > 1) throw new IllegalStateException("expected at most 1, got " + all.size());

try {
    return nativeQuery.singleResult();
} catch (FlowableException e) {
    if (e.getMessage().contains("instead of max 1")) {
        return nativeQuery.list().get(0);
    }
    throw e;
}

When it happens

Trigger: Calling nativeQuery().singleResult() (or executeSingleResult) when the native SQL matches multiple rows — e.g. missing LIMIT 1 or a WHERE clause that isn't unique.

Common situations: Native SQL without LIMIT/TOP returned several matches; unique constraint assumptions broken by duplicate rows; developer used singleResult() assuming at most one row.

Related errors

• Query return " + results.size() + " results instead of max 1
• Query return " + results.size() + " results instead of max 1
• activatedBefore is null
• activity tenant id is null
• activity tenant id is null

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/15243d590c484b78. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-engine-common/src/main/java/org/flowable/common/engine/impl/query/AbstractNativeQuery.java:133

        }
    }

    public abstract long executeCount(CommandContext commandContext, Map<String, Object> parameterMap);

    /**
     * Executes the actual query to retrieve the list of results.
     *
     * @param commandContext
     * @param parameterMap
     */
    public abstract List<U> executeList(CommandContext commandContext, Map<String, Object> parameterMap);

    public U executeSingleResult(CommandContext commandContext) {
        List<U> results = executeList(commandContext, generateParameterMap());
        if (results.size() == 1) {
            return results.get(0);
        } else if (results.size() > 1) {
            throw new FlowableException("Query return " + results.size() + " results instead of max 1");
        }
        return null;
    }

}

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