flowable/flowable-engine · error · ActivitiIllegalArgumentException

Description is null

Error message

Description is null

What it means

TaskQuery.taskDescription(String) requires a non-null exact description value. A null would not define a usable equality filter, so the engine throws ActivitiIllegalArgumentException during query construction.

Solutions

1. Skip the filter when description is null: guard with an if-check before calling
2. Use taskDescriptionLike with a non-null pattern if partial matching is intended (still guard for null)
3. Validate at the API layer that a description filter is only sent when present

Example fix

// before
query.taskDescription(task.getDescription()); // may be null
// after
if (task.getDescription() != null) {
    query.taskDescription(task.getDescription());
}

if (description == null) { /* omit exact-description filter */ }

void addDescriptionFilter(TaskQuery query, String description) {
    if (description != null) {
        query.taskDescription(description);
    }
}

try {
    query.taskDescription(description);
} catch (org.activiti.engine.ActivitiIllegalArgumentException e) {
    // description was null; rebuild without the filter
}

When it happens

Trigger: Calling taskDescription(null), commonly when the description comes from a task variable, DTO field, or request parameter that was absent.

Common situations: Filtering tasks by a description copied from another entity that may lack one; deserialized JSON missing the description key; DB joins producing null descriptions.

Related errors

• None of the given process categories can be null
• Priority is null
• Task descriptionlike is null
• Task descriptionLikeIgnoreCase is null
• Task namelike is null

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/615eddd36b5d76ef. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable5-engine/src/main/java/org/activiti/engine/impl/TaskQueryImpl.java:260

    @Override
    public TaskQuery taskNameLikeIgnoreCase(String nameLikeIgnoreCase) {
        if (nameLikeIgnoreCase == null) {
            throw new ActivitiIllegalArgumentException("Task nameLikeIgnoreCase is null");
        }

        if (orActive) {
            currentOrQueryObject.nameLikeIgnoreCase = nameLikeIgnoreCase.toLowerCase();
        } else {
            this.nameLikeIgnoreCase = nameLikeIgnoreCase.toLowerCase();
        }
        return this;
    }

    @Override
    public TaskQueryImpl taskDescription(String description) {
        if (description == null) {
            throw new ActivitiIllegalArgumentException("Description is null");
        }

        if (orActive) {
            currentOrQueryObject.description = description;
        } else {
            this.description = description;
        }
        return this;
    }

    @Override
    public TaskQuery taskDescriptionLike(String descriptionLike) {
        if (descriptionLike == null) {
            throw new ActivitiIllegalArgumentException("Task descriptionlike is null");
        }
        if (orActive) {
            currentOrQueryObject.descriptionLike = descriptionLike;
        } else {

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