<p dir="auto">It seems passing argument <code class="notranslate">allow_nan = False</code> to <code class="notranslate">flask.jsonify</code> will not actually turn <code class="notranslate">NaN</code>s into something else like <code class="notranslate">null</code> - e.g. <code class="notranslate">flask.jsonify({“a” : numpy.nan})</code> will produce <code class="notranslate">{“a” : NaN}</code></p>
<h3 dir="auto">Expected Behavior</h3>
<p dir="auto">Should be able to run flask with FLASK_ENV=development or production</p>
<h3 dir="auto">Actual Behavior</h3>
<p dir="auto">I get the output</p>
<ul dir="auto">
<li>Serving Flask app "simple" (lazy loading)</li>
<li>Environment: production<br>
WARNING: This is a development server. Do not use it in a production deployment.<br>
Use a production WSGI server instead.</li>
<li>Debug mode: on</li>
<li>Restarting with stat<br>
c:\users\Riprock\Projects\simple s&amp;r\venv\scripts\python.exe: No module named C:\Users\Riprock\Projects\Simple S&amp;R\venv\Scripts\flask</li>
</ul>
<h3 dir="auto">Environment</h3>
<ul dir="auto">
<li>Python version: 3.7.4</li>
<li>Flask version: 1.1.1</li>
<li>Werkzeug version:  0.15.5</li>
</ul>
<p dir="auto">I can't seem to get a flask server running after updating to the latest version of Flask and python. Before the update my FLASK_ENV=development and FLASK_DEBUG=1. Then I updated and started to encounter the error. I tried rebuilding my venv and getting the same error.</p>