flowable/flowable-engine · error · FlowableIllegalArgumentException

userId and groupId cannot both be null

Error message

userId and groupId cannot both be null

What it means

When adding an identity link to a case definition, at least one of userId or groupId must be provided; both being null means there is no identity to link, so validateParams throws FlowableIllegalArgumentException.

Source

Thrown at modules/flowable-cmmn-engine/src/main/java/org/flowable/cmmn/engine/impl/cmd/AddIdentityLinkForCaseDefinitionCmd.java:58

    protected String groupId;

    public AddIdentityLinkForCaseDefinitionCmd(String caseDefinitionId, String userId, String groupId,
            CmmnEngineConfiguration cmmnEngineConfiguration) {
        
        validateParams(userId, groupId, caseDefinitionId);
        this.caseDefinitionId = caseDefinitionId;
        this.userId = userId;
        this.groupId = groupId;
        this.cmmnEngineConfiguration = cmmnEngineConfiguration;
    }

    protected void validateParams(String userId, String groupId, String caseDefinitionId) {
        if (caseDefinitionId == null) {
            throw new FlowableIllegalArgumentException("caseDefinitionId is null");
        }

        if (userId == null && groupId == null) {
            throw new FlowableIllegalArgumentException("userId and groupId cannot both be null");
        }
    }

    @Override
    public Void execute(CommandContext commandContext) {
        CaseDefinitionEntity caseDefinition = cmmnEngineConfiguration.getCaseDefinitionEntityManager().findById(caseDefinitionId);

        if (caseDefinition == null) {
            throw new FlowableObjectNotFoundException("Cannot find case definition with id " + caseDefinitionId, CaseDefinition.class);
        }

        IdentityLinkEntity identityLinkEntity = cmmnEngineConfiguration.getIdentityLinkServiceConfiguration().getIdentityLinkService()
                .createScopeDefinitionIdentityLink(caseDefinition.getId(), ScopeTypes.CMMN, userId, groupId);
        caseDefinition.getIdentityLinks().add(identityLinkEntity);

        return null;
    }

View on GitHub (pinned to d6d39ce1c6)

Solutions

1. Provide either a userId or a groupId (and a matching identityIdType) for the link
2. Validate in the UI/service layer that at least one identity field is set before calling the API
3. If neither applies, skip creating the identity link entirely rather than calling with nulls

Example fix

// before
repositoryService.addIdentityLink(defId, userId, groupId, type); // both null
// after
if (userId == null && groupId == null) {
    throw new IllegalArgumentException("userId or groupId must be provided");
}
repositoryService.addIdentityLink(defId, userId, groupId, type);

if (userId == null && groupId == null) throw new IllegalArgumentException("userId or groupId must be provided");
repositoryService.addIdentityLink(defId, userId, groupId, type);

boolean hasIdentityTarget(String userId, String groupId) { return userId != null || groupId != null; }

try {
    repositoryService.addIdentityLink(defId, userId, groupId, type);
} catch (FlowableIllegalArgumentException e) {
    log.warn("Identity link skipped: {}", e.getMessage());
}

When it happens

Trigger: Calling cmmnRepositoryService.addIdentityLink(caseDefinitionId, null, null, type) — e.g. both user and group variables null after failed lookups, or a form where neither field was filled.

Common situations: Candidate-starter configuration screens submitting empty user+group, data-migration scripts with blank identity columns, or wrong variable wiring so both arguments bind to null.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• type is required when adding a new task identity link
• Either set the user id or the group id for an identity link,
• taskId is null
• identityId is null
• identityIdType allowed values are 1 and 2

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/ee243c4663658b0d. Report an issue: GitHub.