Exception: Failed to find input channel class for X. Unknown input channel. ...

[sentry-io]

Sentry Issue: RASA-OPEN-SOURCE-4G

ImportError: cannot import name 'INTENT_MESSAGE_PREFIX'
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...
  File "rasa/core/run.py", line 64, in _create_single_channel
    channel
  File "rasa/shared/utils/common.py", line 19, in class_from_module_path
    m = importlib.import_module(module_name)

Exception: Failed to find input channel class for X. Unknown input channel. Check your credentials configuration to make sure the mentioned channel is not misspelled. If you are creating your own channel, make sure it is a proper name of a class in a module.
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...
  File "rasa/run.py", line 58, in run
    **kwargs,
  File "rasa/core/run.py", line 175, in serve_application
    input_channels = create_http_input_channels(channel, credentials)
  File "rasa/core/run.py", line 52, in create_http_input_channels
    return [_create_single_channel(c, k) for c, k in all_credentials.items()]
  File "rasa/core/run.py", line 52, in <listcomp>
    return [_create_single_channel(c, k) for c, k in all_credentials.items()]
  File "rasa/core/run.py", line 73, in _create_single_channel
    "is a proper name of a class in a module.".format(channel)