flowable/flowable-engine · error · FlowableIllegalArgumentException

IdentityId is required.

Error message

IdentityId is required.

What it means

validateIdentityLinkArguments requires a non-null identityId path variable identifying the user or group of the identity link. A null identityId throws FlowableIllegalArgumentException("IdentityId is required.").

Solutions

1. Supply the user or group id in the identityId path segment.
2. Validate the id is non-null before invoking the REST call.
3. Check URL templates are fully interpolated.

Example fix

// before
call("/cmmn-runtime/case-instances/case-1/identitylinks/users//participant")
// after
call("/cmmn-runtime/case-instances/case-1/identitylinks/users/kermit/participant")

// Java
if (identityId == null || identityId.isEmpty()) {
    throw new IllegalArgumentException("identityId is required");
}

When it happens

Trigger: GET or DELETE .../identitylinks/{family}/{identityId}/{type} with a missing/empty {identityId} path segment resolved to null by the caller.

Common situations: Template URLs left with unfilled placeholders; clients dropping the identity segment when building the URL programmatically.

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.
• A group or a user is required to create an identity link.
• Identity link family should be 'users' or 'groups'.
• IdentityId is required.
• Only one of user or group can be used to create an identity…

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/d158b4684e2b5cc8. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-cmmn-rest/src/main/java/org/flowable/cmmn/rest/service/api/runtime/caze/CaseInstanceIdentityLinkResource.java:105

        if (restApiInterceptor != null) {
            restApiInterceptor.deleteCaseInstanceIdentityLink(caseInstance, link);
        }

        if (CmmnRestUrls.SEGMENT_IDENTITYLINKS_FAMILY_GROUPS.equals(family)) {
            runtimeService.deleteGroupIdentityLink(caseInstance.getId(), identityId, type);
            
        } else {
            runtimeService.deleteUserIdentityLink(caseInstance.getId(), identityId, type);
        }
    }

    protected void validateIdentityLinkArguments(String family, String identityId, String type) {
        if (family == null || (!CmmnRestUrls.SEGMENT_IDENTITYLINKS_FAMILY_GROUPS.equals(family) && !CmmnRestUrls.SEGMENT_IDENTITYLINKS_FAMILY_USERS.equals(family))) {
            throw new FlowableIllegalArgumentException("Identity link family should be 'users' or 'groups'.");
        }
        if (identityId == null) {
            throw new FlowableIllegalArgumentException("IdentityId is required.");
        }
        if (type == null) {
            throw new FlowableIllegalArgumentException("Type is required.");
        }
    }

    protected IdentityLink getIdentityLink(String identityId, String family, String type, String caseInstanceId) {
        // Perhaps it would be better to offer getting a single identity link
        // from the API
        List<IdentityLink> allLinks = runtimeService.getIdentityLinksForCaseInstance(caseInstanceId);
        for (IdentityLink link : allLinks) {
            if (CmmnRestUrls.SEGMENT_IDENTITYLINKS_FAMILY_USERS.equals(family) && identityId.equals(link.getUserId()) && link.getType().equals(type)) {
                return link;
            
            } else if (CmmnRestUrls.SEGMENT_IDENTITYLINKS_FAMILY_GROUPS.equals(family) && identityId.equals(link.getGroupId()) && link.getType().equals(type)) {
                return link;
            }
        }

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