Worked on stabilizing and maintaining the ILIAS-eLearning/ILIAS repository by addressing critical backend issues in PHP. Focused on resolving two fatal errors that impacted course mapping and course duplication workflows, ensuring smoother user experiences and reducing system downtime. Applied strong debugging and code review skills to correct data type handling in the course mapping pipeline and implemented robust data integrity checks for feedback and answer relationships during course copying. Demonstrated attention to maintainable patching and adherence to codebase conventions, contributing to the reliability of large-scale PHP applications through targeted bug fixes and backend development over a two-month period.