flowable/flowable-engine · error · FlowableIllegalArgumentException

userId and groupId cannot both be null

Error message

userId and groupId cannot both be null

What it means

DeleteIdentityLinkCmd.validateParams throws FlowableIllegalArgumentException when, for a non-assignee/owner type, both userId and groupId are null. Without at least one identity, there is no link to identify and delete.

Source

Thrown at modules/flowable-cmmn-engine/src/main/java/org/flowable/cmmn/engine/impl/cmd/DeleteIdentityLinkCmd.java:66

    }

    protected void validateParams(String userId, String groupId, String type, String taskId) {
        if (taskId == null) {
            throw new FlowableIllegalArgumentException("taskId is null");
        }

        if (type == null) {
            throw new FlowableIllegalArgumentException("type is required when adding a new task identity link");
        }

        // Special treatment for assignee and owner: group cannot be used and userId may be null
        if (IdentityLinkType.ASSIGNEE.equals(type) || IdentityLinkType.OWNER.equals(type)) {
            if (groupId != null) {
                throw new FlowableIllegalArgumentException("Incompatible usage: cannot use type '" + type + "' together with a groupId");
            }
        } else {
            if (userId == null && groupId == null) {
                throw new FlowableIllegalArgumentException("userId and groupId cannot both be null");
            }
        }
    }

    @Override
    protected Void execute(CommandContext commandContext, TaskEntity task) {
        CmmnEngineConfiguration cmmnEngineConfiguration = CommandContextUtil.getCmmnEngineConfiguration(commandContext);
        if (IdentityLinkType.ASSIGNEE.equals(type)) {
            TaskHelper.changeTaskAssignee(task, null, cmmnEngineConfiguration);
        } else if (IdentityLinkType.OWNER.equals(type)) {
            TaskHelper.changeTaskOwner(task, null, cmmnEngineConfiguration);
        } else {
            IdentityLinkUtil.deleteTaskIdentityLinks(task, userId, groupId, type, cmmnEngineConfiguration);
        }

        return null;
    }

View on GitHub (pinned to d6d39ce1c6)

Solutions

1. Provide either the userId or the groupId of the link to remove.
2. Guard at the call site: require at least one non-null identity before invoking the delete.

Example fix

// before
taskService.deleteTaskIdentityLink(taskId, null, null, IdentityLinkType.CANDIDATE);
// after
if (userId == null && groupId == null) throw new IllegalArgumentException("userId or groupId required");
taskService.deleteTaskIdentityLink(taskId, userId, groupId, IdentityLinkType.CANDIDATE);

if (userId == null && groupId == null) throw new IllegalArgumentException("userId or groupId required");

try { taskService.deleteTaskIdentityLink(taskId, userId, groupId, type); } catch (FlowableIllegalArgumentException e) { log.error("Identity link delete requires userId or groupId"); }

When it happens

Trigger: Calling taskService.deleteTaskIdentityLink with a type like CANDIDATE but null userId and null groupId, e.g. when both came from optional request fields.

Common situations: REST/service layers with optional parameters silently forwarding nulls; cleanup jobs iterating link data where fields were never populated.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• type is required when adding a new task identity link
• userId and groupId cannot both be null
• Job {jobId} parent is not CMMN case
• Either set the user id or the group id for an identity link,
• taskId is null

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/957ad3b8206da0e7. Report an issue: GitHub.