Basic Flask app not running (TypeError: required field "type_ignores" missing from Module)

Question

I have a very basic flask app with dependencies installed from my requirements.txt. All of these dependencies are installed in my virtual environment.

requirements.txt given below,

aniso8601==6.0.0
Click==7.0
Flask==1.0.3
Flask-Cors==3.0.7
Flask-RESTful==0.3.7
Flask-SQLAlchemy==2.4.0
itsdangerous==1.1.0
Jinja2==2.10.1
MarkupSafe==1.1.1
# psycopg2-binary==2.8.2
pytz==2019.1
six==1.12.0
# SQLAlchemy==1.3.4
Werkzeug==0.15.4
python-dotenv
requests
authlib

My code in NewTest.py file,

from flask import Flask, request, jsonify, abort, url_for

app = Flask(__name__)

@app.route('/')
def index():
    return jsonify({
        'success': True,
        'index': 'Test Pass'
    })



if __name__ == '__main__':
    app.run(debug=True)

When I run the app through,

export FLASK_APP=NewTest.py
export FLASK_ENV=development
export FLASK_DEBUG=true

    flask run
or flask run --reload

I get the following error,

127.0.0.1 - - [09/Feb/2020 12:43:40] "GET / HTTP/1.1" 500 -
Traceback (most recent call last):
  File "/projects/env/lib/python3.8/site-packages/flask/_compat.py", line 36, i
n reraise
    raise value
  File "/projects/NewTest.py", line 3, in <module>
    app = Flask(__name__)
  File "/projects/env/lib/python3.8/site-packages/flask/app.py", line 559, in _
_init__
    self.add_url_rule(
  File "/projects/env/lib/python3.8/site-packages/flask/app.py", line 67, in wr
apper_func
    return f(self, *args, **kwargs)
  File "/projects/env/lib/python3.8/site-packages/flask/app.py", line 1217, in 
add_url_rule
    self.url_map.add(rule)
  File "/projects/env/lib/python3.8/site-packages/werkzeug/routing.py", line 1388, in add
    rule.bind(self)
  File "/projects/env/lib/python3.8/site-packages/werkzeug/routing.py", line 730, in bind
    self.compile()
  File "/projects/env/lib/python3.8/site-packages/werkzeug/routing.py", line 794, in compile
    self._build = self._compile_builder(False).__get__(self, None)
  File "/projects/env/lib/python3.8/site-packages/werkzeug/routing.py", line 951, in _compile_builder
    code = compile(module, "<werkzeug routing>", "exec")
TypeError: required field "type_ignores" missing from Module

Can anyone please point out what am I missing or doing wrong and how can I fix it? Thanks.

Answer 1

The bug was fixed in werkzeug 0.15.5. Upgrade from 0.15.4 to to a later version.