jupyter notebook: 500: internal server error

Hi, recently, I installed the `jupyter` in my Centos6.5 system, but when I type the command `jupyter notebook` on the terminal, the jupyter website can be open, but when I chose to opoen the `.pynb` format file in browser, it returns `500: internal server error` . I have asked the [OpenPMD_viewer](https://github.com/openPMD/openPMD-viewer) for help, which can be found the issue [here](https://github.com/openPMD/openPMD-viewer/issues/236) for detail, but the expert there couldn't give a better suggestion to help me to solve this issure, so can anyone here could help me ? Thank you very much ! I have tried to `pip install --upgrade --user nbconvert`, but it doesn't works

No source file or test is named. Reproduce `jupyter notebook` on CentOS 6.5, open a `.pynb` file, and inspect the server output for the 500 error; compare the result after upgrading `nbconvert`. Done means identifying the cause and confirming that notebooks open successfully.

Written by the indexing model from the issue text.