flowable/flowable-engine · error · FlowableIllegalArgumentException

Unsupported variable query operation: " + variable.getVariab

Error message

Unsupported variable query operation: " + variable.getVariableOperation()

What it means

The addVariables switch handles the full set of supported VariableQueryOperand values; an unrecognized or unimplemented variableOperation falls into the default branch and throws FlowableIllegalArgumentException. This protects the query API from silently ignoring malformed operations.

Source

Thrown at modules/flowable-rest/src/main/java/org/flowable/rest/service/api/history/HistoricProcessInstanceBaseResource.java:394

            case LESS_THAN:
                processInstanceQuery.variableValueLessThan(variable.getName(), actualValue);
                break;

            case LESS_THAN_OR_EQUALS:
                processInstanceQuery.variableValueLessThanOrEqual(variable.getName(), actualValue);
                break;

            case EXISTS:
                processInstanceQuery.variableExists(variable.getName());
                break;

            case NOT_EXISTS:
                processInstanceQuery.variableNotExists(variable.getName());
                break;

            default:
                throw new FlowableIllegalArgumentException("Unsupported variable query operation: " + variable.getVariableOperation());
            }
        }
    }
}

View on GitHub (pinned to d6d39ce1c6)

Solutions

Use one of the supported operations: EQUALS, NOT_EQUALS, EQUALS_IGNORE_CASE, NOT_EQUALS_IGNORE_CASE, LIKE, LIKE_IGNORE_CASE, GREATER_THAN, GREATER_THAN_OR_EQUAL, LESS_THAN, LESS_THAN_OR_EQUAL, EXISTS, NOT_EXISTS
Check for typos and exact casing of variableOperation in the request JSON
Verify the client's targeted Flowable REST version supports the operation being sent

Example fix

// before
{"name":"status","value":"open","variableOperation":"equal"}
// after
{"name":"status","value":"open","variableOperation":"EQUALS"}

Defensive patterns

Strategy: validation

Validate before calling

const OPS = ['EQUALS','NOT_EQUALS','EQUALS_IGNORE_CASE','NOT_EQUALS_IGNORE_CASE','LIKE','LIKE_IGNORE_CASE','GREATER_THAN','GREATER_THAN_OR_EQUAL','LESS_THAN','LESS_THAN_OR_EQUAL','EXISTS','NOT_EXISTS']; if (!OPS.includes(variable.variableOperation)) throw new Error('Unsupported operation: ' + variable.variableOperation);

Type guard

const isValidOp = (op) => OPS.includes(op);

Try / catch

catch (e) { if (e.response && e.response.status === 400 && /Unsupported variable query operation/.test(e.response.data.message)) { /* fix operation and retry */ } throw e; }

Prevention

Centralize the enum of valid operations in the client
Never send null variableOperation unless using EXISTS/NOT_EXISTS which ignore value
Pin client SDK to the server's Flowable version

When it happens

Trigger: Sending a variable query entry whose variableOperation is null, misspelled, or an enum value not supported for historic process instance queries (e.g. an operation only valid elsewhere in the API).

Common situations: Typos in variableOperation strings in hand-written JSON; clients written against a different Flowable REST version with additional operations; deserialization producing an unexpected enum/null value.

Related errors

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/e40a384a2d961c26. Report an issue: GitHub.