Can you walk us through how you set up your jupyter instance? If we can recreate your error, we'll be able to help much faster. What's the command you're using to set it up, on which OS are you running it and so on 🙂 Also, have you checked your jupyter server is running on port 8888? Chances are something else is using 8888, so jupyter might be running on some other port like 8889 instead, so ClearML is trying to get a kernel from a completely different service.