Context: Traditionally, trainees are instructed to practise with as few errors as possible during simulation-based training. However, transfer of learning may improve if trainees are encouraged to commit errors. The aim of this study was to assess the effects of error management instructions compared with error avoidance instructions during simulation-based ultrasound training. Methods: Medical students (n = 60) with no prior ultrasound experience were randomised to error management training (EMT) (n = 32) or error avoidance training (EAT) (n = 28). The EMT group was instructed to deliberately make errors during training. The EAT group was instructed to follow the simulator instructions and to commit as few errors as possible. Training consisted of 3 hours of simulation-based ultrasound training focusing on fetal weight estimation. Simulation-based tests were administered before and after training. Transfer tests were performed on real patients 7–10 days after the completion of training. Primary outcomes were transfer test performance scores and diagnostic accuracy. Secondary outcomes included performance scores and diagnostic accuracy during the simulation-based pre- and post-tests. Results: A total of 56 participants completed the study. On the transfer test, EMT group participants attained higher performance scores (mean score: 67.7%, 95% confidence interval [CI]: 62.4–72.9%) than EAT group members (mean score: 51.7%, 95% CI: 45.8–57.6%) (p < 0.001; Cohen's d = 1.1, 95% CI: 0.5–1.7). There was a moderate improvement in diagnostic accuracy in the EMT group compared with the EAT group (16.7%, 95% CI: 10.2–23.3% weight deviation versus 26.6%, 95% CI: 16.5–36.7% weight deviation [p = 0.082; Cohen's d = 0.46, 95% CI: −0.06 to 1.0]). No significant interaction effects between group and performance improvements between the pre- and post-tests were found in either performance scores (p = 0.25) or diagnostic accuracy (p = 0.09). Conclusions: The provision of error management instructions during simulation-based training improves the transfer of learning to the clinical setting compared with error avoidance instructions. Rather than teaching to avoid errors, the use of errors for learning should be explored further in medical education theory and practice.