flowable/flowable-engine · error · FlowableIllegalArgumentException

taskId is required

Error message

taskId is required

What it means

The GetEntityLinkParentsForTaskCmd constructor rejects a null taskId immediately with FlowableIllegalArgumentException. Flowable requires a concrete task id to look up parent entity links, so constructing the command with null is invalid by contract.

Source

Thrown at modules/flowable-engine/src/main/java/org/flowable/engine/impl/cmd/GetEntityLinkParentsForTaskCmd.java:40

import org.flowable.common.engine.impl.interceptor.CommandContext;
import org.flowable.engine.impl.cfg.ProcessEngineConfigurationImpl;
import org.flowable.engine.impl.persistence.entity.ExecutionEntity;
import org.flowable.engine.impl.util.CommandContextUtil;
import org.flowable.entitylink.api.EntityLink;
import org.flowable.entitylink.api.EntityLinkType;
import org.flowable.task.service.impl.persistence.entity.TaskEntity;

/**
 * @author Javier Casal
 */
public class GetEntityLinkParentsForTaskCmd implements Command<List<EntityLink>>, Serializable {

    private static final long serialVersionUID = 1L;
    protected String taskId;

    public GetEntityLinkParentsForTaskCmd(String taskId) {
        if (taskId == null) {
            throw new FlowableIllegalArgumentException("taskId is required");
        }
        this.taskId = taskId;
    }

    @Override
    public List<EntityLink> execute(CommandContext commandContext) {
        ProcessEngineConfigurationImpl processEngineConfiguration = CommandContextUtil.getProcessEngineConfiguration(commandContext);
        TaskEntity task = processEngineConfiguration.getTaskServiceConfiguration().getTaskService().getTask(taskId);

        if (task == null) {
            throw new FlowableObjectNotFoundException("Cannot find task with id " + taskId, ExecutionEntity.class);
        }

        return processEngineConfiguration.getEntityLinkServiceConfiguration().getEntityLinkService()
                .findEntityLinksByReferenceScopeIdAndType(task.getId(), ScopeTypes.TASK, EntityLinkType.CHILD);
    }

}

View on GitHub (pinned to d6d39ce1c6)

Solutions

1. Null-check taskId before invoking the service method or constructing the command.
2. Ensure upstream code populated the task id (from TaskEntity.getId() or the API request).
3. Return a client-side validation error (400) when the id field is absent instead of reaching the engine.
4. Use Optional/Objects.requireNonNull at your service boundary to fail fast with a clear message.

Example fix

// before
runtimeService.getEntityLinkParentsForTask(taskId); // taskId may be null
// after
Objects.requireNonNull(taskId, "taskId is required");
runtimeService.getEntityLinkParentsForTask(taskId);

if (taskId == null || taskId.isBlank()) {
    throw new IllegalArgumentException("taskId is required");
}

try {
    taskService.getEntityLinkParentsForTask(taskId);
} catch (FlowableIllegalArgumentException e) {
    // caller bug: null taskId; reject at request-validation layer
}

When it happens

Trigger: new GetEntityLinkParentsForTaskCmd(null) or calling TaskService/RuntimeService wrapper methods that construct this command when the caller's taskId variable is null (e.g. from an unbound delegation or missing task payload).

Common situations: Task id field missing from a request DTO; a previous lookup returning null and the null being passed downstream; deserialization skipping the id property.

Related errors

• task is null
• Error retrieving app engine info
• No deployment id available
• No resource name available
• appsDefinitionIds is null

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/a71222582ac535b2. Report an issue: GitHub.