Jsonnet configuration file cannot be interpreted

As a beginner of Allennlp, I am now trying to reimplement an example. However, when I train the model using the configure method. One traceback pops out:
WARNING - allennlp.common.params - _jsonnet not loaded, treating examples/xxx.jsonnet as json
The jsonnet syntax cannot be interpreted unless I degrade it to json syntax. Does anyone know how to solve this?

It looks like that message is coming from here: https://github.com/allenai/allennlp/blob/master/allennlp/common/params.py#L18

Are you using Windows? Loading JSONNET is causing an error so AllenNLP is falling back on JSON. If you are not on Windows, I would try pip install jsonnet and troubleshoot any errors you get.