flowable/flowable-engine · error · FlowableIllegalArgumentException

Unsupported variable query operation: " +…

Error message

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

What it means

addVariables throws this FlowableIllegalArgumentException when the request's variable query filter specifies a variableOperation value that does not match any supported enum case (EQUALS, NOT_EQUALS, EQUALS_IGNORE_CASE, LIKE, GREATER_THAN, etc.). The default branch of the switch is the guard against unknown/misspelled operations.

Solutions

Use an exact, supported operation name: 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 the VariableQueryOperation enum in your Flowable version and align the client
Log the failing request body to identify the malformed operation value

Example fix

// before
{"name":"status","operation":"contains","value":"run"}
// after
{"name":"status","operation":"like","value":"%run%"}

Defensive patterns

Strategy: validation

Validate before calling

const ALLOWED = ['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 (!ALLOWED.includes(operation)) throw new Error('Unsupported variableOperation: ' + operation);

Type guard

function isValidOperation(op, allowed) { return allowed.includes(op); }

Try / catch

try { await query(body); } catch (e) { if (e.message.startsWith('Unsupported variable query operation')) { console.error('Bad operation:', body.variable.variableOperation); } }

Prevention

Copy operation names exactly from the VariableQueryOperation enum in your Flowable version
Pin the Flowable version and regenerate clients after upgrades
Use an enum type in your client code instead of free-form strings

When it happens

Trigger: Sending a variableQuery with an operation string that is not part of the VariableQueryOperation enum, e.g. "equal", "contains", "", or a typo like "euals"; calling the endpoint after a Flowable upgrade that renamed an operation.

Common situations: Hand-written query strings with wrong casing ("equalsignorecase"); client code built against a different Flowable version; generic UIs letting users type arbitrary operation names.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/ee290230e0f6956d. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-rest/src/main/java/org/flowable/rest/service/api/runtime/process/BaseProcessInstanceResource.java:369

            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());
            }
        }
    }

    /**
     * Returns the {@link ProcessInstance} that is requested and calls the access interceptor.
     * Throws the right exceptions when bad request was made or instance was not found.
     */
    protected ProcessInstance getProcessInstanceFromRequest(String processInstanceId) {
        ProcessInstance processInstance = getProcessInstanceFromRequestWithoutAccessCheck(processInstanceId);

        if (restApiInterceptor != null) {
            restApiInterceptor.accessProcessInstanceInfoById(processInstance);
        }

        return processInstance;
    }

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