flowable/flowable-engine · error · ActivitiIllegalArgumentException

Involved user is null

Error message

Involved user is null

What it means

ProcessInstanceQuery.involvedUser() rejects a null user id. Involvement is tracked via identity links, and a null user cannot match any identity-link row, so the library fails fast with ActivitiIllegalArgumentException rather than building a query with a meaningless null filter.

Solutions

1. Check the user id for null before calling involvedUser and skip the filter when absent.
2. Resolve the current authenticated user first and reject requests without one.
3. Catch ActivitiIllegalArgumentException around query building to return a 400-style validation response.
4. Log the call site where the null id originates to fix the upstream data flow.

Example fix

// before
query.involvedUser(userId); // userId may be null

// after
if (userId != null) {
    query.involvedUser(userId);
}

if (userId == null || userId.isBlank()) {
    throw new IllegalArgumentException("involvedUser id must not be null");
}
query.involvedUser(userId);

boolean hasUserId(String userId) {
    return userId != null && !userId.isBlank();
}

try {
    query.involvedUser(userId);
} catch (org.activiti.engine.ActivitiIllegalArgumentException e) {
    // handle null user, e.g. return empty result or 400
}

When it happens

Trigger: Calling processInstanceQuery().involvedUser(null), typically when the userId variable passed from an upstream layer (session, request parameter, task assignee lookup) is null.

Common situations: Unauthenticated or anonymous users reaching a 'my involved processes' page; a user id lookup that returned null before building the query; optional request parameters mapped straight into the query call.

Related errors

• name is null
• value is null
• category is null
• categoryLike is null
• categoryNotEquals is null

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/eb030f091419cc50. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable5-engine/src/main/java/org/activiti/engine/impl/ProcessInstanceQueryImpl.java:346

            this.subProcessInstanceId = subProcessInstanceId;
        }
        return this;
    }

    @Override
    public ProcessInstanceQuery excludeSubprocesses(boolean excludeSubprocesses) {
        if (inOrStatement) {
            this.currentOrQueryObject.excludeSubprocesses = excludeSubprocesses;
        } else {
            this.excludeSubprocesses = excludeSubprocesses;
        }
        return this;
    }

    @Override
    public ProcessInstanceQuery involvedUser(String involvedUser) {
        if (involvedUser == null) {
            throw new ActivitiIllegalArgumentException("Involved user is null");
        }

        if (inOrStatement) {
            this.currentOrQueryObject.involvedUser = involvedUser;
        } else {
            this.involvedUser = involvedUser;
        }
        return this;
    }

    @Override
    public ProcessInstanceQuery active() {
        if (inOrStatement) {
            this.currentOrQueryObject.suspensionState = SuspensionState.ACTIVE;
        } else {
            this.suspensionState = SuspensionState.ACTIVE;
        }
        return this;

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