The objective of this paper is to develop a robust error-resilient algorithm, called the Synchronous Backward Error Tracking (SBET), to completely terminate the error propagation effects in the error-prone environment for H.264 video coding. The motivation is that if the state of the decoder is available to the encoder, i.e., the state of the encoder can synchronize to the state of the decoder, the effect of error propagation can be entirely terminated because all predictions are based on the same references. Therefore, we assume that a feedback channel is available and the encoder can be aware of the decoder's error concealment by any external means. The pixel-based Precise Backward Error Tracking (PBET) is modified and utilized to track the error locations and reconstruct the state of the decoder in the encoder. The proposed method only involves memory access, simple addition and multiplication operations for the error-contaminated pixels to achieve encoder-decoder synchronization. By observing simulation results, the rate-distortion performance of the proposed algorithm is always better than that of the conventional algorithms. Specifically, SBET outperforms PBET up to 1.21 dB under 3% slice error rate for the QCIF format Foreman sequence. In addition, instead of forced INTRA refreshing, the phenomenon of burst bit rate can be avoided.