无法呈现 Flask 网页

Question

I am using Ubuntu 16.04. It had builtin Python 3.5. I was unable to download Flask in that version. So, I changed it to Anaconda Python3.8.

However, I am unable to render any Flask page.

The following command output shows that, when I run app.py of my Flask application, the web server doesn't return any web-appress:

(base) user_1@dell-vostro:~$ cd git

(base) user_1@dell-vostro:~/git$ cd MyFlaskProject1/

(base) user_1@dell-vostro:~/git/MyFlaskProject1$ python3.5 app.py

Traceback (most recent call last):
  File "app.py", line 1, in <module>
    from flask import Flask, render_template, jsonify
  File "/usr/local/lib/python3.5/dist-packages/flask/__init__.py", line 4, in <module>
    from . import json as json
  File "/usr/local/lib/python3.5/dist-packages/flask/json/__init__.py", line 1
    from __future__ import annotations
SyntaxError: future feature annotations is not defined

(base) user_1@dell-vostro:~/git/MyFlaskProject1$ python3.8 app.py
 * Restarting with inotify reloader
 * Debugger is active!
 * Debugger PIN: 107-653-334

Then, I manually entered 127.0.0.1:5000 in the web-browser, but I see nothing.

How can I solve this issue?

Answer 1

Please try to upgrade your virtual environment from 3.5 as this import is available from 3.7 version hope it will resolve your issue after upgradation.