Prevention of errors has been an orienting goal within the field of Human-Computer Interaction since its inception, with particular focus on minimizing human errors through appropriate technology design. However, there has been relatively little exploration into how designers can best support users of technologies that will inevitably make errors. We present a mixed-methods study in the domain of navigation technology for visually impaired individuals. We examined how users respond to device errors made in realistic scenarios of use. Contrary to conventional wisdom that usable systems must be error-free, we found that 42% of errors were acceptable to users. Acceptance of errors depends on error type, building feature, and environmental context. Further, even when a technical error is acceptable to the user, the misguided social responses of others nearby can negatively impact user experience. We conclude with design recommendations that embrace errors while also supporting user management of errors in technical systems.