flowable/flowable-engine · error · FlowableIllegalArgumentException

Incompatible usage: cannot use type

Error message

Incompatible usage: cannot use type '${type}' together with a groupId

What it means

DeleteIdentityLinkCmd rejects semantically invalid combinations: ASSIGNEE and OWNER links apply to a single user, so a groupId is incompatible; for all other types, at least one of userId or groupId must be provided. Violations throw FlowableIllegalArgumentException.

Solutions

1. For ASSIGNEE/OWNER types pass only a userId and null groupId
2. For other types ensure exactly the relevant id (userId or groupId) is non-null
3. Split the removal logic into user-link and group-link branches instead of one generic call

Example fix

// before
taskService.deleteGroupIdentityLink(taskId, groupId, IdentityLinkType.ASSIGNEE); // incompatible
// after
taskService.deleteUserIdentityLink(taskId, userId, IdentityLinkType.ASSIGNEE);

boolean valid;
if (IdentityLinkType.ASSIGNEE.equals(type) || IdentityLinkType.OWNER.equals(type)) {
    valid = groupId == null;
} else {
    valid = userId != null || groupId != null;
}
if (!valid) {
    throw new IllegalArgumentException("Invalid identity link argument combination for type " + type);
}

boolean isValidLinkCombo = (type, userId, groupId) ->
    (IdentityLinkType.ASSIGNEE.equals(type) || IdentityLinkType.OWNER.equals(type))
        ? groupId == null
        : userId != null || groupId != null;

try {
    taskService.deleteGroupIdentityLink(taskId, groupId, type);
} catch (FlowableIllegalArgumentException e) {
    logger.warn("Incompatible identity link arguments", e);
}

When it happens

Trigger: deleteUserIdentityLink/deleteGroupIdentityLink calls where type is ASSIGNEE or OWNER but a groupId is passed, or where both userId and groupId are null for any other type.

Common situations: Copy-paste between user and group link APIs, generic link-removal helpers that pass both userId/groupId through unchecked, or code computing type dynamically (assignee) while still supplying a group id.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• A group or a user is required to create an identity link.
• Only one of user or group can be used to create an identity…
• type is required when adding a new case instance identity…
• type is required when adding a new process instance…
• userId and groupId cannot both be null

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/eae430ce7b3112fa. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-engine/src/main/java/org/flowable/engine/impl/cmd/DeleteIdentityLinkCmd.java:65

        this.taskId = taskId;
        this.userId = userId;
        this.groupId = groupId;
        this.type = type;
    }

    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) {
        if (task.getProcessDefinitionId() != null && Flowable5Util.isFlowable5ProcessDefinitionId(commandContext, task.getProcessDefinitionId())) {
            Flowable5CompatibilityHandler compatibilityHandler = Flowable5Util.getFlowable5CompatibilityHandler();
            compatibilityHandler.deleteIdentityLink(taskId, userId, groupId, type);
            return null;
        }

        if (IdentityLinkType.ASSIGNEE.equals(type)) {
            TaskHelper.changeTaskAssignee(task, null);

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