🐞 TypeError: The view function for 'main' did not return a valid response. #137

tgotwig · 2022-06-27T09:20:40Z

Did it like described in https://github.com/rycus86/prometheus_flask_exporter#usage but with app.run(debug=True) at the end? 🤔

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    <title>TypeError: The view function for 'main' did not return a valid response. The function either returned None or ended without a return statement.
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<h1>TypeError</h1>
<div class="detail">
  <p class="errormsg">TypeError: The view function for &#x27;main&#x27; did not return a valid response. The function either returned None or ended without a return statement.
</p>
</div>
<h2 class="traceback">Traceback <em>(most recent call last)</em></h2>
<div class="traceback">
  <h3></h3>
  <ul><li><div class="frame" id="frame-4369751440">
  <h4>File <cite class="filename">"/Users/tgotwig/.asdf/installs/python/3.10.5/lib/python3.10/site-packages/flask/app.py"</cite>,
      line <em class="line">2095</em>,
      in <code class="function">__call__</code></h4>
  <div class="source "><pre class="line before"><span class="ws">    </span>def __call__(self, environ: dict, start_response: t.Callable) -&gt; t.Any:</pre>
<pre class="line before"><span class="ws">        </span>&quot;&quot;&quot;The WSGI server calls the Flask application object as the</pre>
<pre class="line before"><span class="ws">        </span>WSGI application. This calls :meth:`wsgi_app`, which can be</pre>
<pre class="line before"><span class="ws">        </span>wrapped to apply middleware.</pre>
<pre class="line before"><span class="ws">        </span>&quot;&quot;&quot;</pre>
<pre class="line current"><span class="ws">        </span>return self.wsgi_app(environ, start_response)</pre></div>
</div>

<li><div class="frame" id="frame-4369752336">
  <h4>File <cite class="filename">"/Users/tgotwig/.asdf/installs/python/3.10.5/lib/python3.10/site-packages/flask/app.py"</cite>,
      line <em class="line">2080</em>,
      in <code class="function">wsgi_app</code></h4>
  <div class="source "><pre class="line before"><span class="ws">            </span>try:</pre>
<pre class="line before"><span class="ws">                </span>ctx.push()</pre>
<pre class="line before"><span class="ws">                </span>response = self.full_dispatch_request()</pre>
<pre class="line before"><span class="ws">            </span>except Exception as e:</pre>
<pre class="line before"><span class="ws">                </span>error = e</pre>
<pre class="line current"><span class="ws">                </span>response = self.handle_exception(e)</pre>
<pre class="line after"><span class="ws">            </span>except:  # noqa: B001</pre>
<pre class="line after"><span class="ws">                </span>error = sys.exc_info()[1]</pre>
<pre class="line after"><span class="ws">                </span>raise</pre>
<pre class="line after"><span class="ws">            </span>return response(environ, start_response)</pre>
<pre class="line after"><span class="ws">        </span>finally:</pre></div>
</div>

<li><div class="frame" id="frame-4369752560">
  <h4>File <cite class="filename">"/Users/tgotwig/.asdf/installs/python/3.10.5/lib/python3.10/site-packages/flask/app.py"</cite>,
      line <em class="line">2077</em>,
      in <code class="function">wsgi_app</code></h4>
  <div class="source "><pre class="line before"><span class="ws">        </span>ctx = self.request_context(environ)</pre>
<pre class="line before"><span class="ws">        </span>error: t.Optional[BaseException] = None</pre>
<pre class="line before"><span class="ws">        </span>try:</pre>
<pre class="line before"><span class="ws">            </span>try:</pre>
<pre class="line before"><span class="ws">                </span>ctx.push()</pre>
<pre class="line current"><span class="ws">                </span>response = self.full_dispatch_request()</pre>
<pre class="line after"><span class="ws">            </span>except Exception as e:</pre>
<pre class="line after"><span class="ws">                </span>error = e</pre>
<pre class="line after"><span class="ws">                </span>response = self.handle_exception(e)</pre>
<pre class="line after"><span class="ws">            </span>except:  # noqa: B001</pre>
<pre class="line after"><span class="ws">                </span>error = sys.exc_info()[1]</pre></div>
</div>

<li><div class="frame" id="frame-4369752224">
  <h4>File <cite class="filename">"/Users/tgotwig/.asdf/installs/python/3.10.5/lib/python3.10/site-packages/flask/app.py"</cite>,
      line <em class="line">1526</em>,
      in <code class="function">full_dispatch_request</code></h4>
  <div class="source "><pre class="line before"><span class="ws">            </span>rv = self.preprocess_request()</pre>
<pre class="line before"><span class="ws">            </span>if rv is None:</pre>
<pre class="line before"><span class="ws">                </span>rv = self.dispatch_request()</pre>
<pre class="line before"><span class="ws">        </span>except Exception as e:</pre>
<pre class="line before"><span class="ws">            </span>rv = self.handle_user_exception(e)</pre>
<pre class="line current"><span class="ws">        </span>return self.finalize_request(rv)</pre>
<pre class="line after"><span class="ws"></span> </pre>
<pre class="line after"><span class="ws">    </span>def finalize_request(</pre>
<pre class="line after"><span class="ws">        </span>self,</pre>
<pre class="line after"><span class="ws">        </span>rv: t.Union[ResponseReturnValue, HTTPException],</pre>
<pre class="line after"><span class="ws">        </span>from_error_handler: bool = False,</pre></div>
</div>

<li><div class="frame" id="frame-4369751328">
  <h4>File <cite class="filename">"/Users/tgotwig/.asdf/installs/python/3.10.5/lib/python3.10/site-packages/flask/app.py"</cite>,
      line <em class="line">1545</em>,
      in <code class="function">finalize_request</code></h4>
  <div class="source "><pre class="line before"><span class="ws">        </span>with the `from_error_handler` flag.  If enabled, failures in</pre>
<pre class="line before"><span class="ws">        </span>response processing will be logged and otherwise ignored.</pre>
<pre class="line before"><span class="ws"></span> </pre>
<pre class="line before"><span class="ws">        </span>:internal:</pre>
<pre class="line before"><span class="ws">        </span>&quot;&quot;&quot;</pre>
<pre class="line current"><span class="ws">        </span>response = self.make_response(rv)</pre>
<pre class="line after"><span class="ws">        </span>try:</pre>
<pre class="line after"><span class="ws">            </span>response = self.process_response(response)</pre>
<pre class="line after"><span class="ws">            </span>request_finished.send(self, response=response)</pre>
<pre class="line after"><span class="ws">        </span>except Exception:</pre>
<pre class="line after"><span class="ws">            </span>if not from_error_handler:</pre></div>
</div>

<li><div class="frame" id="frame-4369752448">
  <h4>File <cite class="filename">"/Users/tgotwig/.asdf/installs/python/3.10.5/lib/python3.10/site-packages/flask/app.py"</cite>,
      line <em class="line">1701</em>,
      in <code class="function">make_response</code></h4>
  <div class="source "><pre class="line before"><span class="ws">                    </span>&quot; (body, status), or (body, headers).&quot;</pre>
<pre class="line before"><span class="ws">                </span>)</pre>
<pre class="line before"><span class="ws"></span> </pre>
<pre class="line before"><span class="ws">        </span># the body must not be None</pre>
<pre class="line before"><span class="ws">        </span>if rv is None:</pre>
<pre class="line current"><span class="ws">            </span>raise TypeError(</pre>
<pre class="line after"><span class="ws">                </span>f&quot;The view function for {request.endpoint!r} did not&quot;</pre>
<pre class="line after"><span class="ws">                </span>&quot; return a valid response. The function either returned&quot;</pre>
<pre class="line after"><span class="ws">                </span>&quot; None or ended without a return statement.&quot;</pre>
<pre class="line after"><span class="ws">            </span>)</pre>
<pre class="line after"><span class="ws"></span> </pre></div>
</div>
</ul>
  <blockquote>TypeError: The view function for &#x27;main&#x27; did not return a valid response. The function either returned None or ended without a return statement.
</blockquote>
</div>

<div class="plain">
    <p>
      This is the Copy/Paste friendly version of the traceback.
    </p>
    <textarea cols="50" rows="10" name="code" readonly>Traceback (most recent call last):
  File &quot;/Users/tgotwig/.asdf/installs/python/3.10.5/lib/python3.10/site-packages/flask/app.py&quot;, line 2095, in __call__
    return self.wsgi_app(environ, start_response)
  File &quot;/Users/tgotwig/.asdf/installs/python/3.10.5/lib/python3.10/site-packages/flask/app.py&quot;, line 2080, in wsgi_app
    response = self.handle_exception(e)
  File &quot;/Users/tgotwig/.asdf/installs/python/3.10.5/lib/python3.10/site-packages/flask/app.py&quot;, line 2077, in wsgi_app
    response = self.full_dispatch_request()
  File &quot;/Users/tgotwig/.asdf/installs/python/3.10.5/lib/python3.10/site-packages/flask/app.py&quot;, line 1526, in full_dispatch_request
    return self.finalize_request(rv)
  File &quot;/Users/tgotwig/.asdf/installs/python/3.10.5/lib/python3.10/site-packages/flask/app.py&quot;, line 1545, in finalize_request
    response = self.make_response(rv)
  File &quot;/Users/tgotwig/.asdf/installs/python/3.10.5/lib/python3.10/site-packages/flask/app.py&quot;, line 1701, in make_response
    raise TypeError(
TypeError: The view function for &#x27;main&#x27; did not return a valid response. The function either returned None or ended without a return statement.
</textarea>
</div>
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<!--

Traceback (most recent call last):
  File "/Users/tgotwig/.asdf/installs/python/3.10.5/lib/python3.10/site-packages/flask/app.py", line 2095, in __call__
    return self.wsgi_app(environ, start_response)
  File "/Users/tgotwig/.asdf/installs/python/3.10.5/lib/python3.10/site-packages/flask/app.py", line 2080, in wsgi_app
    response = self.handle_exception(e)
  File "/Users/tgotwig/.asdf/installs/python/3.10.5/lib/python3.10/site-packages/flask/app.py", line 2077, in wsgi_app
    response = self.full_dispatch_request()
  File "/Users/tgotwig/.asdf/installs/python/3.10.5/lib/python3.10/site-packages/flask/app.py", line 1526, in full_dispatch_request
    return self.finalize_request(rv)
  File "/Users/tgotwig/.asdf/installs/python/3.10.5/lib/python3.10/site-packages/flask/app.py", line 1545, in finalize_request
    response = self.make_response(rv)
  File "/Users/tgotwig/.asdf/installs/python/3.10.5/lib/python3.10/site-packages/flask/app.py", line 1701, in make_response
    raise TypeError(
TypeError: The view function for 'main' did not return a valid response. The function either returned None or ended without a return statement.


-->

The text was updated successfully, but these errors were encountered:

rycus86 · 2022-06-27T10:05:37Z

I should probably update those examples to return something valid, sorry. 🤦
As the error message explains:

The function either returned None or ended without a return statement.

If you change the pass to something like return 'OK' then it should work.

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🐞 TypeError: The view function for 'main' did not return a valid response. #137

🐞 TypeError: The view function for 'main' did not return a valid response. #137

tgotwig commented Jun 27, 2022 •

edited

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rycus86 commented Jun 27, 2022

🐞 TypeError: The view function for 'main' did not return a valid response. #137

🐞 TypeError: The view function for 'main' did not return a valid response. #137

Comments

tgotwig commented Jun 27, 2022 • edited Loading

rycus86 commented Jun 27, 2022

tgotwig commented Jun 27, 2022 •

edited

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