I believe the issue is that https://github.com/lightstep/lightstep-tracer-python/blob/master/lightstep/crouton/ttypes.py was generated with 0.9.2, but lightstep now requires 0.10.0. Accessing the accelerated module appears to have changed since 0.10.0 (https://github.com/apache/thrift/pull/844). I recommend you re-generate the thrift code with a newer version of the Thrift compiler.