title: Internal server error while using flask in cs50 ide
body: <p>The code's all correct but am not able to show out the desirable output on the browser- the browser alerts an internal server message(500) and the terminal shows the following error:</p>
  <blockquote>
  <p>~/tracks/ $ flask run  * Serving Flask app &quot;application.py&quot; (lazy
  loading)  * Environment: development  * Debug mode: off  * Running on
  <a href="https://3405db29-f322-4a37-845f-11d0e562946b-ide.cs50.xyz:8080/" rel="nofollow noreferrer">https://3405db29-f322-4a37-845f-11d0e562946b-ide.cs50.xyz:8080/</a> (Press
  CTRL+C to quit)  * Restarting with stat [2020-09-13 07:29:50,889]
  ERROR in app: Exception on / [GET] Traceback (most recent call last):
  File &quot;/usr/local/lib/python3.7/site-packages/flask/app.py&quot;, line 2446,
  in wsgi_app
  response = self.full_dispatch_request()   File &quot;/usr/local/lib/python3.7/site-packages/flask/app.py&quot;, line 1951, in
  full_dispatch_request
  rv = self.handle_user_exception(e)   File &quot;/usr/local/lib/python3.7/site-packages/flask/app.py&quot;, line 1820, in
  handle_user_exception
  reraise(exc_type, exc_value, tb)   File &quot;/usr/local/lib/python3.7/site-packages/flask/_compat.py&quot;, line 39, in
  reraise
  raise value   File &quot;/usr/local/lib/python3.7/site-packages/flask/app.py&quot;, line 1949, in
  full_dispatch_request
  rv = self.dispatch_request()   File &quot;/usr/local/lib/python3.7/site-packages/flask/app.py&quot;, line 1935, in
  dispatch_request
  return self.view_functionsrule.endpoint   File &quot;/home/ubuntu/tracks/application.py&quot;, line 10, in index
  return render_template(&quot;index.html&quot;, number=number)   File &quot;/usr/local/lib/python3.7/site-packages/flask/templating.py&quot;, line
  138, in render_template
  ctx.app.jinja_env.get_or_select_template(template_name_or_list),   File &quot;/usr/local/lib/python3.7/site-packages/jinja2/environment.py&quot;,
  line 930, in get_or_select_template
  return self.get_template(template_name_or_list, parent, globals)   File &quot;/usr/local/lib/python3.7/site-packages/jinja2/environment.py&quot;,
  line 883, in get_template
  return self._load_template(name, self.make_globals(globals))   File &quot;/usr/local/lib/python3.7/site-packages/jinja2/environment.py&quot;,
  line 857, in _load_template
  template = self.loader.load(self, name, globals)   File &quot;/usr/local/lib/python3.7/site-packages/jinja2/loaders.py&quot;, line 117,
  in load
  source, filename, uptodate = self.get_source(environment, name)   File &quot;/usr/local/lib/python3.7/site-packages/flask/templating.py&quot;,
  line 60, in get_source<br />
  return self._get_source_fast(environment, template)   File &quot;/usr/local/lib/python3.7/site-packages/flask/templating.py&quot;, line 89,
  in _get_source_fast<br />
  raise TemplateNotFound(template) jinja2.exceptions.TemplateNotFound: index.html<br />
  192.168.74.236 - - [13/Sep/2020 07:29:50] &quot;GET / HTTP/1.0&quot; 500 -</p>
  </blockquote>