<p dir="auto">The vanilla command to activate the development server is documented as:</p>
<p dir="auto">$ flask --app hello run --debug</p>
<p dir="auto">on</p>
<p dir="auto"><a href="https://flask.palletsprojects.com/en/2.2.x/server/" rel="nofollow">https://flask.palletsprojects.com/en/2.2.x/server/</a>   copyright 2010 (Really, no changes since 2010?)</p>
<p dir="auto">no longer works.  Specifically the '--debug' option seems to be obsolete.</p>
<p dir="auto">$ flask run --help     says use</p>
<p dir="auto">--debugger / --no-debugger  and strongly implies that the debugger is on by default (although there is room for a different interpretation).</p>
<p dir="auto">The web page and help are not aligned.</p>
<p dir="auto">Replication:</p>
<p dir="auto">$ flask --app flasker run --debug    produces an error</p>
<p dir="auto">$ flask --app flaskr run --debugger   starts the development server.</p>
<p dir="auto">I did not check if the debugger is on by default</p>
<p dir="auto">Describe the expected behavior that should have happened but didn't:</p>
<p dir="auto">Per <a href="https://flask.palletsprojects.com/en/2.2.x/server/" rel="nofollow">https://flask.palletsprojects.com/en/2.2.x/server/</a></p>
<p dir="auto">$ flask --app hello run --debug</p>
<p dir="auto">should start the development server.</p>
<p dir="auto">Environment:</p>
<ul dir="auto">
<li>Python version: 3.11.0</li>
<li>Flask version:  2.2.2</li>
<li>Werkzeug: 2.2.2</li>
<li>Windows: Microsoft Windows 11 Pro, 10.0.22623 Build 22623</li>
</ul>
<blockquote>
<p dir="auto">Python 3.9.13<br>
Flask 2.2.2<br>
Werkzeug 2.2.2</p>
</blockquote>
<p dir="auto">The docs, in more than one place:</p>
<ul dir="auto">
<li><a href="https://flask.palletsprojects.com/en/2.2.x/quickstart/#debug-mode" rel="nofollow">https://flask.palletsprojects.com/en/2.2.x/quickstart/#debug-mode</a></li>
<li><a href="https://flask.palletsprojects.com/en/2.2.x/server/#command-line" rel="nofollow">https://flask.palletsprojects.com/en/2.2.x/server/#command-line</a></li>
</ul>
<p dir="auto">say to run <code class="notranslate">flask run --debug</code> but that doesn't actually work:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="Usage: flask run [OPTIONS]
Try 'flask run --help' for help.

Error: No such option: --debug (Possible options: --debugger, --no-debugger)"><pre class="notranslate"><code class="notranslate">Usage: flask run [OPTIONS]
Try 'flask run --help' for help.

Error: No such option: --debug (Possible options: --debugger, --no-debugger)
</code></pre></div>
<p dir="auto">You need to run <code class="notranslate">flask --debug run </code></p>