Worked on stabilizing the UF2 bootloader file transfer process in the renesas/zephyr repository, focusing on resolving a cross-platform crash that affected Windows users. Addressed a specific OSError by replacing shutil.copy() with shutil.copyfile() in the Python-based flashing workflow, thereby preventing permission-related failures during the unmount window after flashing. This change aligned the process with FAT filesystem limitations and Windows-specific behavior, improving reliability for end users. Demonstrated strong skills in error handling and file handling, with careful attention to maintainability and traceability through explicit commit references and signed-off patches. Delivered a more robust and predictable flashing experience for Windows environments.