flowable/flowable-engine · error · FlowableException

Cannot assign a groupId to a task assignment that already…

Error message

Cannot assign a groupId to a task assignment that already has a userId

What it means

IdentityLinkEntityImpl.setGroupId is the counterpart guard: assigning a non-null groupId when userId is already set throws this FlowableException. A runtime identity link must model either a user assignment or a group assignment, not both.

Solutions

1. Create separate identity links for user and group assignments.
2. Call setUserId(null) before setting a groupId if converting the link type is intentional.
3. Fix the source configuration (BPMN candidate settings or assignment handler) so user and group targets never land on the same entity.

Example fix

// before
identityLink.setUserId("kermit");
identityLink.setGroupId("sales"); // throws

// after
identityLink.setUserId(null);
identityLink.setGroupId("sales");

if (identityLink.getUserId() != null && groupId != null) {
    throw new IllegalArgumentException("Split user and group into separate identity links");
}

try {
    identityLink.setGroupId(groupId);
} catch (FlowableException e) {
    // fall back to creating a fresh IdentityLinkEntity for the group
}

When it happens

Trigger: getDefaultIdentityLinks or custom code calling setGroupId on an IdentityLinkEntity whose userId is already non-null, e.g. converting a candidate-user link to a candidate-group link in place.

Common situations: Task definitions with overlapping candidateUser/candidateGroup configuration feeding one link; custom assignment listeners reusing an existing link entity; tests constructing links with both fields set.

Related errors

• Cannot assign a userId to a task assignment that already…
• Cannot assign a groupId to a task assignment that already…
• Cannot assign a userId to a task assignment that already…
• Cannot assign a groupId to a task assignment that already…
• Cannot assign a groupId to a task assignment that already…

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/c3f28f53db073520. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-identitylink-service/src/main/java/org/flowable/identitylink/service/impl/persistence/entity/IdentityLinkEntityImpl.java:142

    }

    @Override
    public void setUserId(String userId) {
        if (this.groupId != null && userId != null) {
            throw new FlowableException("Cannot assign a userId to a task assignment that already has a groupId");
        }
        this.userId = userId;
    }

    @Override
    public String getGroupId() {
        return groupId;
    }

    @Override
    public void setGroupId(String groupId) {
        if (this.userId != null && groupId != null) {
            throw new FlowableException("Cannot assign a groupId to a task assignment that already has a userId");
        }
        this.groupId = groupId;
    }

    @Override
    public String getTaskId() {
        return taskId;
    }

    @Override
    public void setTaskId(String taskId) {
        this.taskId = taskId;
    }

    @Override
    public String getProcessInstanceId() {
        return processInstanceId;
    }

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