Worked on enhancing reliability and error handling in the symfony/symfony and symfony/serializer repositories by addressing issues in denormalization error collection. Focused on backend development using PHP and Symfony, the developer fixed bugs where denormalization errors were not properly captured when specific flags were set in the default context. The approach included implementing targeted unit and end-to-end tests to ensure multiple errors are now consistently reported to clients, improving error visibility and reducing debugging time. These changes aligned error collection behavior across related repositories, resulting in more predictable and maintainable backend systems for applications relying on Symfony components.