Calling startstreamtranscription from a Python 3.7 app inside a Ubuntu 16.04 based Docker container crashed with RuntimeError: 1033 (AWSIOTLSCTXERROR): Failed to create tls context. The traceback came from awscrt's io.ClientTlsContext during session setup. The maintainers could not reproduce it on a clean Ubuntu 16.04 image and suspected a missing system library for encryption. The reporter found that installing the ssh package in the Dockerfile made the code run perfectly.