quarkusio/quarkus · error · UnsupportedOperationException

Cannot sort by nulls first or nulls last

Error message

Cannot sort by nulls first or nulls last

What it means

When converting a Panache Sort to a MongoDB sort Document, any column with a non-null nullPrecedence (nulls first/last, from Sort.nullsFirst()/nullsLast()) throws UnsupportedOperationException because MongoDB's sort documents cannot express null-ordering semantics the way SQL does.

Source

Thrown at extensions/panache/mongodb-panache-common/runtime/src/main/java/io/quarkus/mongodb/panache/common/reactive/runtime/ReactiveMongoOperations.java:609

        return createQuery(collection, null, null);
    }

    public QueryType findAll(Class<?> entityClass, Sort sort) {
        ReactiveMongoCollection collection = mongoCollection(entityClass);
        Bson sortDoc = sortToDocument(sort);
        return createQuery(collection, null, sortDoc);
    }

    private Bson sortToDocument(Sort sort) {
        if (sort == null) {
            return null;
        }

        Document sortDoc = new Document();
        for (Sort.Column col : sort.getColumns()) {
            sortDoc.append(col.getName(), col.getDirection() == Sort.Direction.Ascending ? 1 : -1);
            if (col.getNullPrecedence() != null) {
                throw new UnsupportedOperationException("Cannot sort by nulls first or nulls last");
            }
        }
        return sortDoc;
    }

    public Uni<List<?>> listAll(Class<?> entityClass) {
        return (Uni) list(findAll(entityClass));
    }

    public Uni<List<?>> listAll(Class<?> entityClass, Sort sort) {
        return (Uni) list(findAll(entityClass, sort));
    }

    public Multi<?> streamAll(Class<?> entityClass) {
        return stream(findAll(entityClass));
    }

    public Multi<?> streamAll(Class<?> entityClass, Sort sort) {

View on GitHub (pinned to e1c734241f)

Solutions

1. Remove nullsFirst()/nullsLast() from the Sort columns when targeting MongoDB
2. If null ordering matters, store an explicit sortable sentinel field or use an aggregation pipeline with $ifNull/$sort instead of a simple sort
3. Filter out null-valued fields in the query so ordering of nulls becomes irrelevant

Example fix

// before
Sort sort = Sort.descending("deletedAt").nullsLast("deletedAt"); // throws

// after
Sort sort = Sort.descending("deletedAt"); // MongoDB default null ordering

boolean hasNullPrecedence = sort.getColumns().stream().anyMatch(c -> c.getNullPrecedence() != null);
if (hasNullPrecedence) throw new IllegalArgumentException("nullsFirst/nullsLast not supported by MongoDB Panache");

try {
    return repository.list(sort);
} catch (UnsupportedOperationException e) {
    return repository.list(sortIgnoringNullPrecedence(sort));
}

When it happens

Trigger: Building a Sort that includes Sort.nullsFirst(...) or Sort.nullsLast(...) and passing it to a reactive MongoDB Panache query (find/list/findAll with sort), which calls getSortDocument.

Common situations: Porting Hibernate ORM/SQL Panache code (where nulls first/last is supported) to MongoDB Panache; sharing a common Sort-building utility between relational and MongoDB repositories; copy-pasted sorting logic that includes null-precedence modifiers.

Related errors

• Cannot call a page related method in a ranged query, call pa
• Cannot call a page related method, call page(Page) or page(i
• Cannot call a page related method in a ranged query, call pa
• Cannot sort by nulls first or nulls last
• Update types are only supported in MongoDB contexts

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/a69a315fe2dd22a9. Report an issue: GitHub.