title: flask-ngrok returns "Tunnel _________.ngrok.io not found" when running flask app via ngrok on Google Colab
body: <p>I was running a &quot;local&quot; web app on Google Colab using flask-ngrok according to this article: <a href="https://medium.com/@kshitijvijay271199/flask-on-google-colab-f6525986797b" rel="noreferrer">Flask on Google Colab</a>. It was working appropriately in the past but today I started to get the error: &quot;Tunnel _______.ngrok.io not found&quot; whenever I try to access the generated public URL by ngrok. Everything was unchanged since the last time when it still worked. I checked the <a href="https://pypi.org/project/flask-ngrok/0.0.25/" rel="noreferrer">flask-ngrok package</a>, looks like the package version remains unchanged since 2018. Couldn't figure out what is going wrong. Any help would be appreciated!</p>
  <pre><code>!pip install flask-ngrok
  
  
  from flask_ngrok import run_with_ngrok
  from flask import Flask
  
  app = Flask(__name__)
  run_with_ngrok(app)   #starts ngrok when the app is run
  
  @app.route(&quot;/&quot;)
  def home():
      return &quot;&lt;h1&gt;Running Flask on Google Colab!&lt;/h1&gt;&quot;
  
  app.run()
  </code></pre>
  <p>Here's another similar article: <a href="https://www.linkedin.com/pulse/running-python-flask-apps-google-colab-biranchi-nayak?articleId=6675616675573964801" rel="noreferrer">Running Python Flask Apps on Google Colab</a>, there is a link to the  <a href="https://colab.research.google.com/drive/1NN06tyHayRA447cMMI787p2NtdvwX_k5#scrollTo=B5TVfkO_9xpm" rel="noreferrer">full code</a> in colab where you can run it yourself. It now gives the same tunnel not found error too.</p>