I get "Internal Server Error" when call Vim_Markdown_Preview()

[pilot513]

When rendered preview in file:///tmp/vim-markdown-preview.html

Internal Server Error
The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.

The grip is installed:

$ pip show grip
Name: grip
Version: 4.6.2
Summary: Render local readme files before sending off to GitHub.
Home-page: http://github.com/joeyespo/grip
Author: Joe Esposito
Author-email: joe@joeyespo.com
License: MIT
Location: /home/lot/.local/lib/python3.10/site-packages
Requires: docopt, Flask, Markdown, path-and-address, Pygments, requests, Werkzeug

What's may be wrong ?

[pilot513]

I'm switched to vim_markdown_preview_pandoc for resolve problem (from vim_markdown_preview_github)