I'm working with python in Jupyter notebook using virtualenv in Ubuntu 16.04 but as soon I create a new file the kernel dies and it happens again and again. This happens although I restarted the whole process again for several times
The error message isn't very descriptive; console output would be very helpful. But I have suspicions you can look into:
First, try increasing memory and cpu for your virtual machine. I have a feeling that the kernel is simply getting starved out.
The other question ([sic] suspicion) I have for you is did you have successful runs with Notebook in the past? If the answer is no, there's probably something wrong with the installation.