flowable/flowable-engine · error · ActivitiIllegalArgumentException

None of the given process instance ids can be null

Error message

None of the given process instance ids can be null

What it means

TaskQueryImpl.processInstanceIdIn(List<String>) iterates the given ids and throws ActivitiIllegalArgumentException if any individual element is null. The engine builds a SQL IN clause from the list, and a null element cannot be bound as a valid process instance id.

Solutions

1. Filter out null (and blank) ids before passing the list: ids.removeIf(Objects::isNull) or build a new filtered list.
2. Validate each id is non-null/non-blank at the boundary where the list is created and fail with a precise message about which entry is bad.
3. Catch ActivitiIllegalArgumentException around query construction and report the invalid id list to the caller.

Example fix

// before
taskQuery.processInstanceIdIn(ids); // ids may contain nulls

// after
List<String> cleanIds = ids.stream()
    .filter(Objects::nonNull)
    .collect(Collectors.toList());
if (!cleanIds.isEmpty()) {
    taskQuery.processInstanceIdIn(cleanIds);
}

List<String> cleanIds = ids == null ? Collections.emptyList()
    : ids.stream().filter(Objects::nonNull).collect(Collectors.toList());
if (!cleanIds.isEmpty()) {
    taskQuery.processInstanceIdIn(cleanIds);
}

boolean hasNoNullEntries(List<String> ids) { return ids != null && ids.stream().allMatch(Objects::nonNull); }

try {
    return taskQuery.processInstanceIdIn(ids).list();
} catch (ActivitiIllegalArgumentException e) {
    log.warn("Null entry in process instance ids: {}", e.getMessage());
    throw new BadRequestException("All process instance ids must be non-null");
}

When it happens

Trigger: Calling taskQuery.processInstanceIdIn(Arrays.asList("id1", null)) or passing a collection produced by a mapping step that inserted nulls (e.g. Map lookups that missed, or a results array with placeholder nulls).

Common situations: Joining ids from external systems where some lookups failed and nulls were kept instead of dropped; deserializing JSON arrays that contain null entries.

Related errors

• Candidate group list is empty
• Candidate group list is null
• Process category list is empty
• Process category list is null
• Process instance id list is empty

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/00d4900a95657989. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable5-engine/src/main/java/org/activiti/engine/impl/TaskQueryImpl.java:627

        if (orActive) {
            currentOrQueryObject.processInstanceId = processInstanceId;
        } else {
            this.processInstanceId = processInstanceId;
        }
        return this;
    }

    @Override
    public TaskQuery processInstanceIdIn(List<String> processInstanceIds) {
        if (processInstanceIds == null) {
            throw new ActivitiIllegalArgumentException("Process instance id list is null");
        }
        if (processInstanceIds.isEmpty()) {
            throw new ActivitiIllegalArgumentException("Process instance id list is empty");
        }
        for (String processInstanceId : processInstanceIds) {
            if (processInstanceId == null) {
                throw new ActivitiIllegalArgumentException("None of the given process instance ids can be null");
            }
        }

        if (orActive) {
            currentOrQueryObject.processInstanceIds = processInstanceIds;
        } else {
            this.processInstanceIds = processInstanceIds;
        }
        return this;
    }

    @Override
    public TaskQueryImpl processInstanceBusinessKey(String processInstanceBusinessKey) {
        if (orActive) {
            currentOrQueryObject.processInstanceBusinessKey = processInstanceBusinessKey;
        } else {
            this.processInstanceBusinessKey = processInstanceBusinessKey;
        }

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