flowable/flowable-engine · error · FlowableIllegalArgumentException

variableNames is null

Error message

variableNames is null

What it means

RemoveVariablesCmd requires a non-null collection of variable names. When variableNames is null it throws FlowableIllegalArgumentException because there is nothing to remove and the command cannot proceed meaningfully.

Solutions

1. Pass an empty collection or skip the call when there are no names, instead of null
2. Normalize collection-returning helpers to return Collections.emptyList()
3. Validate the input collection before invoking

Example fix

// before
cmmnRuntimeService.removeVariables(caseInstanceId, names); // names may be null
// after
cmmnRuntimeService.removeVariables(caseInstanceId, names == null ? Collections.emptyList() : names);

List<String> safeNames = names == null ? Collections.emptyList() : names;

try { cmmnRuntimeService.removeVariables(id, names); } catch (FlowableIllegalArgumentException e) { log.error("Invalid variableNames: {}", e.getMessage()); }

When it happens

Trigger: Calling removeVariables(caseInstanceId, null); commonly the names collection came from a null-valued field, an absent request body entry, or a method returning null instead of an empty collection.

Common situations: Jackson deserializing missing JSON arrays to null; helper methods returning null on no-match instead of Collections.emptyList(); refactors changing a single-name API to a collection API.

Related errors

• caseInstanceId is null
• caseInstanceId is null
• caseInstanceId is null
• caseInstanceId is null
• caseInstanceId is null

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/15d6b651c19fa1ca. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-cmmn-engine/src/main/java/org/flowable/cmmn/engine/impl/cmd/RemoveVariablesCmd.java:43

 * @author Tijs Rademakers
 */
public class RemoveVariablesCmd implements Command<Void> {
    
    protected String caseInstanceId;
    protected Collection<String> variableNames;
    
    public RemoveVariablesCmd(String caseInstanceId, Collection<String> variableNames) {
        this.caseInstanceId = caseInstanceId;
        this.variableNames = variableNames;
    }
    
    @Override
    public Void execute(CommandContext commandContext) {
        if (caseInstanceId == null) {
            throw new FlowableIllegalArgumentException("caseInstanceId is null");
        }
        if (variableNames == null) {
            throw new FlowableIllegalArgumentException("variableNames is null");
        }
     
        CaseInstanceEntity caseInstanceEntity = CommandContextUtil.getCaseInstanceEntityManager(commandContext).findById(caseInstanceId);
        if (caseInstanceEntity == null) {
            throw new FlowableObjectNotFoundException("No case instance found for id " + caseInstanceId, CaseInstanceEntity.class);
        }
        caseInstanceEntity.removeVariables(variableNames);
        
        return null;
    }

}

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