Worked on the zephyrproject-rtos/zephyr-testing repository, focusing on improving the reliability of Modbus client error handling within embedded systems. Addressed a specific issue in the Modbus client’s write response validation by updating the error signaling from ENXIO to -EIO using C programming, ensuring that write errors are now correctly indicated. This targeted bug fix enhanced the observability of Modbus write failures, reducing ambiguity in system logs and enabling faster diagnosis for downstream automation stacks. The patch was submitted with proper sign-off and prepared for integration and CI validation, reflecting a methodical approach to embedded systems reliability and maintainability.