Failed to load model class 'SigmaModel'

[MAGALLANESJoseManuel]

Failed to load model class 'SigmaModel' from module 'ipysigma'
Error: No version of module ipysigma is registered
at f.loadClass (http://localhost:8888/lab/extensions/@jupyter-widgets/jupyterlab-manager/static/134.b4eddbb09f5fd50a4007.js?v=b4eddbb09f5fd50a4007:1:74934)
at f.loadModelClass (http://localhost:8888/lab/extensions/@jupyter-widgets/jupyterlab-manager/static/336.9f709c2076672b1bfe2b.js?v=9f709c2076672b1bfe2b:1:10729)
at f._make_model (http://localhost:8888/lab/extensions/@jupyter-widgets/jupyterlab-manager/static/336.9f709c2076672b1bfe2b.js?v=9f709c2076672b1bfe2b:1:7517)
at f.new_model (http://localhost:8888/lab/extensions/@jupyter-widgets/jupyterlab-manager/static/336.9f709c2076672b1bfe2b.js?v=9f709c2076672b1bfe2b:1:5137)
at f.handle_comm_open (http://localhost:8888/lab/extensions/@jupyter-widgets/jupyterlab-manager/static/336.9f709c2076672b1bfe2b.js?v=9f709c2076672b1bfe2b:1:3894)
at _handleCommOpen (http://localhost:8888/lab/extensions/@jupyter-widgets/jupyterlab-manager/static/134.b4eddbb09f5fd50a4007.js?v=b4eddbb09f5fd50a4007:1:73471)
at v._handleCommOpen (http://localhost:8888/static/notebook/3676.bundle.js:1:30809)
at async v._handleMessage (http://localhost:8888/static/notebook/3676.bundle.js:1:32703)

[Yomguithereal]

This tends to happen with some Jupyter versions. Try relaunching everything (and clear the cell's output and cache also).