flowable/flowable-engine · error · FlowableIllegalArgumentException

name is empty

Error message

name is empty

What it means

InternalVariableInstanceQueryImpl.name(String) requires a non-empty variable name because variables are looked up by their name column. An empty name cannot identify a variable, so FlowableIllegalArgumentException("name is empty") is thrown at InternalVariableInstanceQueryImpl.java:194.

Solutions

1. Pass the actual variable name, e.g. query.name("orderStatus").
2. Filter empty names out of the list before adding name(...) calls.
3. Skip the name(...) call (or use nameLike with a valid pattern) when the name is unknown.

Example fix

// before
for (String n : names) {
    query.name(n); // throws if n is ""
}

// after
for (String n : names) {
    if (StringUtils.isNotEmpty(n)) {
        query.name(n);
    }
}

if (variableName == null || variableName.isEmpty()) {
    throw new IllegalArgumentException("variableName must be non-empty");
}

try {
    query.name(variableName);
} catch (FlowableIllegalArgumentException e) {
    log.warn("Skipping empty variable name filter");
}

When it happens

Trigger: Calling query.name("") or query.name(null); StringUtils.isEmpty triggers the exception.

Common situations: Variable name sourced from user input, a map key, or a constant that was never initialized; loops iterating over a variable-name list containing an empty entry.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

• scopeType is empty
• appsDefinitionIds is null
• Booleans and null cannot be used in 'greater than' condition
• Booleans and null cannot be used in 'greater than or equal'…
• Booleans and null cannot be used in 'less than' condition

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/ba49cc6ad5c50777. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-variable-service/src/main/java/org/flowable/variable/service/impl/InternalVariableInstanceQueryImpl.java:194

    @Override
    public InternalVariableInstanceQuery scopeType(String scopeType) {
        if (StringUtils.isEmpty(scopeType)) {
            throw new FlowableIllegalArgumentException("scopeType is empty");
        }
        this.scopeType = scopeType;
        return this;
    }

    @Override
    public InternalVariableInstanceQuery scopeTypes(Collection<String> scopeTypes) {
        this.scopeTypes = scopeTypes;
        return this;
    }

    @Override
    public InternalVariableInstanceQuery name(String name) {
        if (StringUtils.isEmpty(name)) {
            throw new FlowableIllegalArgumentException("name is empty");
        }
        this.name = name;
        return this;
    }

    @Override
    public InternalVariableInstanceQuery names(Collection<String> names) {
        this.names = names;
        return this;
    }

    @Override
    public List<VariableInstanceEntity> list() {
        return dataManager.findVariablesInstancesByQuery(this);
    }

    @Override
    public VariableInstanceEntity singleResult() {

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