Flask - ImportError: No module named app

__init__.py is imported using a directory. if you want to import it as app you should put __init__.py file in directory named app

a better option is just to rename __init__.py to app.py

This is probably an error in flask application's folder structure.
Anyone looking for a simple beginner-friendly structure for the flask project may find this helpful:

   |__movies 
     |__run.py 
     |__app     
        ├── templates
        │   └── index.html
        │   └── signup.html
        └── __init__.py
        └── routes.py

Here 'movies' is the name given for the main application. It contains 'run.py' and a folder called 'app'. 'app' folder contains all necessary flask files such as 'templates' folder, '__init __.py', and 'routes.py'.

Contents of:

run.py:

from app import app

__init__.py:

from flask import Flask

app = Flask(__name__)

from app import routes


app.run(debug=True)

routes.py:

from app import app

@app.route('/')
@app.route('/index')
def index():
    return "Hello, World!"