This research aims to determine the percentage of errors in solving trigonometry problems based on Newman's Error Analysis and to identify the most common errors made by students. The types of errors analyzed include (1) reading errors, (2) comprehension errors, (3) transformation errors, (4) process skill errors, and (5) encoding errors. This study uses a descriptive research method. Data was collected through a written test, and data analysis was conducted using the Miles and Huberman model. The subjects were grade XI-MIPA students at SMA Negeri 2 Padangsidimpuan, North Sumatra, Indonesia, during the odd semester from July to December of the 2025/2026 academic year. The results show the following error percentages: reading errors at 5%, comprehension errors at 55.4%, transformation errors at 64.6%, process skill errors at 65%, and encoding errors at 80.9%. The most prevalent error among students was in encoding the final answer, with a rate of 80.9%. This indicates that while students could often understand and begin transforming the problem, a significant majority struggled with correctly and completely writing the final solution. The findings suggest that instructional focus should be intensified on the final stages of problem-solving, particularly on systematic calculation, verification, and proper presentation of answers.