We've had about 200 occurrences of this error in various parts of our code. I have captured stack traces using sentry so I may be able to provide more detail if requested. The ultimate problem is that a SystemError is raised from within contextlib. The message of the SystemError is:

"<class 'contextlib._GeneratorContextManager'> returned a result with an error set"

The code, according to sentry, that is emitting this error is:

python3.6/contextlib.py in helper at line 159
            <cleanup>
    """
    @wraps(func)
    def helper(*args, **kwds):
>        return _GeneratorContextManager(func, args, kwds)
    return helper

I'm reporting this bug primarily because of the documentation at https://docs.python.org/3/library/exceptions.html#SystemError and I'm using CPython