Ex50 Internal Server Error

[BennettInHouston]

I received " Internal Server Error" when I run the code.

Here is the code:

from flask import Flask
from flask import render_template

app = Flask(__name__)

@app.route ('/')

def index ():
        greeting = "Hello World"
        return render_template ("index.html", greeting=greeting)

if __name__ == "__main__":
    app.run ()

How can I resolve this issue. I tried both Windows 8 and 10, I got the same error.

[gpkesley]

Looks like typos to me. You have a spaces in a lot of places before before the parenthesis (call).

This might be how you’ve posted the code here but if not, fix that.

I.e

def index (): 
render_template (‘index.html’)

To

def index():
render_template(‘index.html’)

[BennettInHouston]

Finally I figured it out. It’s the folder structure issue.

My original folder structure is like this:

gothonweb/
        gothonweb/
                app.py
        templates/
        docs/
        bin/
        tests/
              test_app.py

I moved the templates folder under gothonweb as follows:

gothonweb/
        gothonweb/
                app.py
                templates/
        docs/
        bin/
        tests/
              test_app.py

Then it works perfectly.

[zedshaw]

Interesting, I’m curious if that’s a recent change in Flask? What version of flask did you install?

Incidentally, @gpkesley the extra space between a function name and the parens isn’t a syntax error. It is inconsistent with how everyone else types code but it’ll still run. @BennettInHouston should stop adding the space mostly because other people will complain about it, not because it’s an error of any syntax.

[bigharpo]

Hi Zed, I followed your instructions to a tee and had the same issues regarding the Internal Server Error. Followed @BennettInHouston file structure and worked perfectly.

Just letting you know my issues and what worked for me

[zedshaw]

That means it’s some code issue, so in the Terminal output you should have a more full description of the error. Can you paste it here?

[bigharpo]

@zedshaw Hope I’ve done this right!

 (lpthw) 192-168-1-102:gothonweb Michael$ python app.py
     * Serving Flask app "app" (lazy loading)
     * Environment: production
       WARNING: This is a development server. Do not use it in a production deployment.
       Use a production WSGI server instead.
     * Debug mode: off
     * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
    [2021-02-02 08:54:42,736] ERROR in app: Exception on / [GET]
    Traceback (most recent call last):
      File "/Users/Michael/.venvs/lpthw/lib/python3.6/site-packages/flask/app.py", line 2447, in wsgi_app
        response = self.full_dispatch_request()
      File "/Users/Michael/.venvs/lpthw/lib/python3.6/site-packages/flask/app.py", line 1952, in full_dispatch_request
        rv = self.handle_user_exception(e)
      File "/Users/Michael/.venvs/lpthw/lib/python3.6/site-packages/flask/app.py", line 1821, in handle_user_exception
        reraise(exc_type, exc_value, tb)
      File "/Users/Michael/.venvs/lpthw/lib/python3.6/site-packages/flask/_compat.py", line 39, in reraise
        raise value
      File "/Users/Michael/.venvs/lpthw/lib/python3.6/site-packages/flask/app.py", line 1950, in full_dispatch_request
        rv = self.dispatch_request()
      File "/Users/Michael/.venvs/lpthw/lib/python3.6/site-packages/flask/app.py", line 1936, in dispatch_request
        return self.view_functions[rule.endpoint](**req.view_args)
      File "app.py", line 9, in index
        return render_template("index.html", greeting=greeting)
      File "/Users/Michael/.venvs/lpthw/lib/python3.6/site-packages/flask/templating.py", line 138, in render_template
        ctx.app.jinja_env.get_or_select_template(template_name_or_list),
      File "/Users/Michael/.venvs/lpthw/lib/python3.6/site-packages/jinja2/environment.py", line 930, in get_or_select_template
        return self.get_template(template_name_or_list, parent, globals)
      File "/Users/Michael/.venvs/lpthw/lib/python3.6/site-packages/jinja2/environment.py", line 883, in get_template
        return self._load_template(name, self.make_globals(globals))
      File "/Users/Michael/.venvs/lpthw/lib/python3.6/site-packages/jinja2/environment.py", line 857, in _load_template
        template = self.loader.load(self, name, globals)
      File "/Users/Michael/.venvs/lpthw/lib/python3.6/site-packages/jinja2/loaders.py", line 115, in load
        source, filename, uptodate = self.get_source(environment, name)
      File "/Users/Michael/.venvs/lpthw/lib/python3.6/site-packages/flask/templating.py", line 60, in get_source
        return self._get_source_fast(environment, template)
      File "/Users/Michael/.venvs/lpthw/lib/python3.6/site-packages/flask/templating.py", line 89, in _get_source_fast
        raise TemplateNotFound(template)
    jinja2.exceptions.TemplateNotFound: index.html
    127.0.0.1 - - [02/Feb/2021 08:54:42] "GET / HTTP/1.1" 500 -

[zedshaw]

It looks like your index.html file is not available. Look at your code and see where it should be, then make sure that file is in the right template location.

[BenSnaas]

Same for me.

When I go like this (as is instructed in the manual):

It does not work.

But when I go like this:

Runs like a charm.

Could be due to some kind of update.

[zedshaw]

I wonder if Flask changed how it loads things, or you’ve configured it to load from a different directory?

[BenSnaas]

If I have done so than I am fully unaware of how I did that xD.

There is something else I have been stuck with myself for some time.

The study drills ask to read about and implement css and html5 files.

So I made these files:

But I cannot get the css implemented in the html file:

It gives the following error when I press f12:

For some reason it thinks there is nothing in the file:

Any idea what I am doing wrong? I have a feeling it has something to with the directories again, but I have been playing around with it for a while and cannot seem to figure it out.

[zedshaw]

For that you need to setup a static/ directory that flask serves, put the static .css and other files in there (images, javascript), and then make your URLs match that. You can see the docs here:

Static Files — Flask Documentation (1.1.x)

And the sample app here:

pallets/flask/blob/1.1.2/examples/tutorial/flaskr/static/style.css

And if you google: “flask static files” or “flask css” this will come up.

[BenSnaas]

Thank you very much!