flowable/flowable-engine · error · ActivitiIllegalArgumentException

categoryNotEquals is null

Error message

categoryNotEquals is null

What it means

ProcessDefinitionQueryImpl.processDefinitionCategoryNotEquals(String) excludes process definitions whose category equals the given value. Flowable throws ActivitiIllegalArgumentException when the value is null, since 'not equals null' cannot be expressed as intended in the query filter.

Source

Thrown at modules/flowable5-engine/src/main/java/org/activiti/engine/impl/ProcessDefinitionQueryImpl.java:114

            throw new ActivitiIllegalArgumentException("category is null");
        }
        this.category = category;
        return this;
    }

    @Override
    public ProcessDefinitionQueryImpl processDefinitionCategoryLike(String categoryLike) {
        if (categoryLike == null) {
            throw new ActivitiIllegalArgumentException("categoryLike is null");
        }
        this.categoryLike = categoryLike;
        return this;
    }

    @Override
    public ProcessDefinitionQueryImpl processDefinitionCategoryNotEquals(String categoryNotEquals) {
        if (categoryNotEquals == null) {
            throw new ActivitiIllegalArgumentException("categoryNotEquals is null");
        }
        this.categoryNotEquals = categoryNotEquals;
        return this;
    }

    @Override
    public ProcessDefinitionQueryImpl processDefinitionName(String name) {
        if (name == null) {
            throw new ActivitiIllegalArgumentException("name is null");
        }
        this.name = name;
        return this;
    }

    @Override
    public ProcessDefinitionQueryImpl processDefinitionNameLike(String nameLike) {
        if (nameLike == null) {
            throw new ActivitiIllegalArgumentException("nameLike is null");

View on GitHub (pinned to d6d39ce1c6)

Solutions

1. Pass a non-null category string to exclude.
2. Null-check the exclusion value; skip the filter when none is specified.
3. Use processDefinitionCategory() instead if you actually want to include one category.
4. Catch ActivitiIllegalArgumentException to report invalid query parameters.

Example fix

// before
query.processDefinitionCategoryNotEquals(excludedCategory); // may be null
// after
if (excludedCategory != null) {
    query.processDefinitionCategoryNotEquals(excludedCategory);
}

if (categoryNotEquals != null && !categoryNotEquals.isEmpty()) {
    query.processDefinitionCategoryNotEquals(categoryNotEquals);
}

boolean hasExclusion(String v) { return v != null && !v.isEmpty(); }

try {
    query.processDefinitionCategoryNotEquals(excluded);
} catch (org.activiti.engine.ActivitiIllegalArgumentException e) {
    throw new BadRequestException("categoryNotEquals requires a non-null value", e);
}

When it happens

Trigger: Calling processDefinitionQuery.processDefinitionCategoryNotEquals(null), often when an exclusion value is conditionally set.

Common situations: Building 'exclude category X' features where X comes from user input or config that is missing; copying filter maps with absent keys directly into the query.

Related errors

• category is null
• categoryLike is null
• name is null
• process definition id is null
• process definition id is null

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/2937184114712e3d. Report an issue: GitHub.