Commutation failure (CF) in line-commutated converter-based high-voltage direct current (LCC-HVDC) systems is a common issue that poses a significant threat to the stability and security of AC-DC hybrid power systems. Typically, CF occurs due to severe AC faults near the inverter station. However, recent experience in China’s LCC-HVDC systems—where the control strategy incorporates saturation and current error control (CEC)—indicates that even a mild voltage droop at the inverter-side AC bus can trigger CF. This paper reveals that while CEC improves the system’s small-signal stability, it can have a detrimental effect on the inverter’s commutation process, potentially causing CF even under non-severe fault conditions. Through detailed modeling and analysis, we demonstrate that, even during mild faults, CEC’s overreaction can unnecessarily increase the inverter's firing angle, reducing the extinction angle below the critical threshold and ultimately leading to CF. This phenomenon, along with the proposed mechanism, is validated through electro-mechanical transient simulations conducted with PSD-BPA program. Additionally, our analysis shows that CF is sensitive to both the HVDC transmission power and control parameters.