<!DOCTYPE html>
<html lang="en" data-content_root="../">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" /><meta name="viewport" content="width=device-width, initial-scale=1" />
<meta property="og:title" content="Exceptions" />
<meta property="og:type" content="website" />
<meta property="og:url" content="https://docs.python.org/3/library/asyncio-exceptions.html" />
<meta property="og:site_name" content="Python documentation" />
<meta property="og:description" content="Source code: Lib/asyncio/exceptions.py" />
<meta property="og:image" content="https://docs.python.org/3/_static/og-image.png" />
<meta property="og:image:alt" content="Python documentation" />
<meta name="description" content="Source code: Lib/asyncio/exceptions.py" />
<meta property="og:image:width" content="200">
<meta property="og:image:height" content="200">
<meta name="theme-color" content="#3776ab">
<title>Exceptions — Python 3.13.3 documentation</title><meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" type="text/css" href="../_static/pygments.css?v=b86133f3" />
<link rel="stylesheet" type="text/css" href="../_static/pydoctheme.css?v=23252803" />
<link id="pygments_dark_css" media="(prefers-color-scheme: dark)" rel="stylesheet" type="text/css" href="../_static/pygments_dark.css?v=5349f25f" />
<script src="../_static/documentation_options.js?v=5d57ca2d"></script>
<script src="../_static/doctools.js?v=9bcbadda"></script>
<script src="../_static/sphinx_highlight.js?v=dc90522c"></script>
<script src="../_static/sidebar.js"></script>
<link rel="search" type="application/opensearchdescription+xml"
title="Search within Python 3.13.3 documentation"
href="../_static/opensearch.xml"/>
<link rel="author" title="About these documents" href="../about.html" />
<link rel="index" title="Index" href="../genindex.html" />
<link rel="search" title="Search" href="../search.html" />
<link rel="copyright" title="Copyright" href="../copyright.html" />
<link rel="next" title="Event Loop" href="asyncio-eventloop.html" />
<link rel="prev" title="Queues" href="asyncio-queue.html" />
<link rel="canonical" href="https://docs.python.org/3/library/asyncio-exceptions.html">
<style>
@media only screen {
table.full-width-table {
width: 100%;
}
}
</style>
<link rel="stylesheet" href="../_static/pydoctheme_dark.css" media="(prefers-color-scheme: dark)" id="pydoctheme_dark_css">
<link rel="shortcut icon" type="image/png" href="../_static/py.svg" />
<script type="text/javascript" src="../_static/copybutton.js"></script>
<script type="text/javascript" src="../_static/menu.js"></script>
<script type="text/javascript" src="../_static/search-focus.js"></script>
<script type="text/javascript" src="../_static/themetoggle.js"></script>
<script type="text/javascript" src="../_static/rtd_switcher.js"></script>
<meta name="readthedocs-addons-api-version" content="1">
</head>
<body>
<div class="mobile-nav">
<input type="checkbox" id="menuToggler" class="toggler__input" aria-controls="navigation"
aria-pressed="false" aria-expanded="false" role="button" aria-label="Menu" />
<nav class="nav-content" role="navigation">
<label for="menuToggler" class="toggler__label">
<span></span>
</label>
<span class="nav-items-wrapper">
<a href="https://www.python.org/" class="nav-logo">
<img src="../_static/py.svg" alt="Python logo"/>
</a>
<span class="version_switcher_placeholder"></span>
<form role="search" class="search" action="../search.html" method="get">
<svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 24 24" class="search-icon">
<path fill-rule="nonzero" fill="currentColor" d="M15.5 14h-.79l-.28-.27a6.5 6.5 0 001.48-5.34c-.47-2.78-2.79-5-5.59-5.34a6.505 6.505 0 00-7.27 7.27c.34 2.8 2.56 5.12 5.34 5.59a6.5 6.5 0 005.34-1.48l.27.28v.79l4.25 4.25c.41.41 1.08.41 1.49 0 .41-.41.41-1.08 0-1.49L15.5 14zm-6 0C7.01 14 5 11.99 5 9.5S7.01 5 9.5 5 14 7.01 14 9.5 11.99 14 9.5 14z"></path>
</svg>
<input placeholder="Quick search" aria-label="Quick search" type="search" name="q" />
<input type="submit" value="Go"/>
</form>
</span>
</nav>
<div class="menu-wrapper">
<nav class="menu" role="navigation" aria-label="main navigation">
<div class="language_switcher_placeholder"></div>
<label class="theme-selector-label">
Theme
<select class="theme-selector" oninput="activateTheme(this.value)">
<option value="auto" selected>Auto</option>
<option value="light">Light</option>
<option value="dark">Dark</option>
</select>
</label>
<div>
<h4>Previous topic</h4>
<p class="topless"><a href="asyncio-queue.html"
title="previous chapter">Queues</a></p>
</div>
<div>
<h4>Next topic</h4>
<p class="topless"><a href="asyncio-eventloop.html"
title="next chapter">Event Loop</a></p>
</div>
<div role="note" aria-label="source link">
<h3>This Page</h3>
<ul class="this-page-menu">
<li><a href="../bugs.html">Report a Bug</a></li>
<li>
<a href="https://github.com/python/cpython/blob/main/Doc/library/asyncio-exceptions.rst"
rel="nofollow">Show Source
</a>
</li>
</ul>
</div>
</nav>
</div>
</div>
<div class="related" role="navigation" aria-label="Related">
<h3>Navigation</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="../genindex.html" title="General Index"
accesskey="I">index</a></li>
<li class="right" >
<a href="../py-modindex.html" title="Python Module Index"
>modules</a> |</li>
<li class="right" >
<a href="asyncio-eventloop.html" title="Event Loop"
accesskey="N">next</a> |</li>
<li class="right" >
<a href="asyncio-queue.html" title="Queues"
accesskey="P">previous</a> |</li>
<li><img src="../_static/py.svg" alt="Python logo" style="vertical-align: middle; margin-top: -1px"/></li>
<li><a href="https://www.python.org/">Python</a> »</li>
<li class="switchers">
<div class="language_switcher_placeholder"></div>
<div class="version_switcher_placeholder"></div>
</li>
<li>
</li>
<li id="cpython-language-and-version">
<a href="../index.html">3.13.3 Documentation</a> »
</li>
<li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> »</li>
<li class="nav-item nav-item-2"><a href="ipc.html" >Networking and Interprocess Communication</a> »</li>
<li class="nav-item nav-item-3"><a href="asyncio.html" accesskey="U"><code class="xref py py-mod docutils literal notranslate"><span class="pre">asyncio</span></code> — Asynchronous I/O</a> »</li>
<li class="nav-item nav-item-this"><a href="">Exceptions</a></li>
<li class="right">
<div class="inline-search" role="search">
<form class="inline-search" action="../search.html" method="get">
<input placeholder="Quick search" aria-label="Quick search" type="search" name="q" id="search-box" />
<input type="submit" value="Go" />
</form>
</div>
|
</li>
<li class="right">
<label class="theme-selector-label">
Theme
<select class="theme-selector" oninput="activateTheme(this.value)">
<option value="auto" selected>Auto</option>
<option value="light">Light</option>
<option value="dark">Dark</option>
</select>
</label> |</li>
</ul>
</div>
<div class="document">
<div class="documentwrapper">
<div class="bodywrapper">
<div class="body" role="main">
<section id="exceptions">
<span id="asyncio-exceptions"></span><h1>Exceptions<a class="headerlink" href="#exceptions" title="Link to this heading">¶</a></h1>
<p><strong>Source code:</strong> <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/3.13/Lib/asyncio/exceptions.py">Lib/asyncio/exceptions.py</a></p>
<hr class="docutils" />
<dl class="py exception">
<dt class="sig sig-object py" id="asyncio.TimeoutError">
<em class="property"><span class="k"><span class="pre">exception</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">TimeoutError</span></span><a class="headerlink" href="#asyncio.TimeoutError" title="Link to this definition">¶</a></dt>
<dd><p>A deprecated alias of <a class="reference internal" href="exceptions.html#TimeoutError" title="TimeoutError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TimeoutError</span></code></a>,
raised when the operation has exceeded the given deadline.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.11: </span>This class was made an alias of <a class="reference internal" href="exceptions.html#TimeoutError" title="TimeoutError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TimeoutError</span></code></a>.</p>
</div>
</dd></dl>
<dl class="py exception">
<dt class="sig sig-object py" id="asyncio.CancelledError">
<em class="property"><span class="k"><span class="pre">exception</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">CancelledError</span></span><a class="headerlink" href="#asyncio.CancelledError" title="Link to this definition">¶</a></dt>
<dd><p>The operation has been cancelled.</p>
<p>This exception can be caught to perform custom operations
when asyncio Tasks are cancelled. In almost all situations the
exception must be re-raised.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.8: </span><a class="reference internal" href="#asyncio.CancelledError" title="asyncio.CancelledError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">CancelledError</span></code></a> is now a subclass of <a class="reference internal" href="exceptions.html#BaseException" title="BaseException"><code class="xref py py-class docutils literal notranslate"><span class="pre">BaseException</span></code></a> rather than <a class="reference internal" href="exceptions.html#Exception" title="Exception"><code class="xref py py-class docutils literal notranslate"><span class="pre">Exception</span></code></a>.</p>
</div>
</dd></dl>
<dl class="py exception">
<dt class="sig sig-object py" id="asyncio.InvalidStateError">
<em class="property"><span class="k"><span class="pre">exception</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">InvalidStateError</span></span><a class="headerlink" href="#asyncio.InvalidStateError" title="Link to this definition">¶</a></dt>
<dd><p>Invalid internal state of <a class="reference internal" href="asyncio-task.html#asyncio.Task" title="asyncio.Task"><code class="xref py py-class docutils literal notranslate"><span class="pre">Task</span></code></a> or <a class="reference internal" href="asyncio-future.html#asyncio.Future" title="asyncio.Future"><code class="xref py py-class docutils literal notranslate"><span class="pre">Future</span></code></a>.</p>
<p>Can be raised in situations like setting a result value for a
<em>Future</em> object that already has a result value set.</p>
</dd></dl>
<dl class="py exception">
<dt class="sig sig-object py" id="asyncio.SendfileNotAvailableError">
<em class="property"><span class="k"><span class="pre">exception</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">SendfileNotAvailableError</span></span><a class="headerlink" href="#asyncio.SendfileNotAvailableError" title="Link to this definition">¶</a></dt>
<dd><p>The “sendfile” syscall is not available for the given
socket or file type.</p>
<p>A subclass of <a class="reference internal" href="exceptions.html#RuntimeError" title="RuntimeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">RuntimeError</span></code></a>.</p>
</dd></dl>
<dl class="py exception">
<dt class="sig sig-object py" id="asyncio.IncompleteReadError">
<em class="property"><span class="k"><span class="pre">exception</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">IncompleteReadError</span></span><a class="headerlink" href="#asyncio.IncompleteReadError" title="Link to this definition">¶</a></dt>
<dd><p>The requested read operation did not complete fully.</p>
<p>Raised by the <a class="reference internal" href="asyncio-stream.html#asyncio-streams"><span class="std std-ref">asyncio stream APIs</span></a>.</p>
<p>This exception is a subclass of <a class="reference internal" href="exceptions.html#EOFError" title="EOFError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">EOFError</span></code></a>.</p>
<dl class="py attribute">
<dt class="sig sig-object py" id="asyncio.IncompleteReadError.expected">
<span class="sig-name descname"><span class="pre">expected</span></span><a class="headerlink" href="#asyncio.IncompleteReadError.expected" title="Link to this definition">¶</a></dt>
<dd><p>The total number (<a class="reference internal" href="functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) of expected bytes.</p>
</dd></dl>
<dl class="py attribute">
<dt class="sig sig-object py" id="asyncio.IncompleteReadError.partial">
<span class="sig-name descname"><span class="pre">partial</span></span><a class="headerlink" href="#asyncio.IncompleteReadError.partial" title="Link to this definition">¶</a></dt>
<dd><p>A string of <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> read before the end of stream was reached.</p>
</dd></dl>
</dd></dl>
<dl class="py exception">
<dt class="sig sig-object py" id="asyncio.LimitOverrunError">
<em class="property"><span class="k"><span class="pre">exception</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">asyncio.</span></span><span class="sig-name descname"><span class="pre">LimitOverrunError</span></span><a class="headerlink" href="#asyncio.LimitOverrunError" title="Link to this definition">¶</a></dt>
<dd><p>Reached the buffer size limit while looking for a separator.</p>
<p>Raised by the <a class="reference internal" href="asyncio-stream.html#asyncio-streams"><span class="std std-ref">asyncio stream APIs</span></a>.</p>
<dl class="py attribute">
<dt class="sig sig-object py" id="asyncio.LimitOverrunError.consumed">
<span class="sig-name descname"><span class="pre">consumed</span></span><a class="headerlink" href="#asyncio.LimitOverrunError.consumed" title="Link to this definition">¶</a></dt>
<dd><p>The total number of to be consumed bytes.</p>
</dd></dl>
</dd></dl>
</section>
<div class="clearer"></div>
</div>
</div>
</div>
<div class="sphinxsidebar" role="navigation" aria-label="Main">
<div class="sphinxsidebarwrapper">
<div>
<h4>Previous topic</h4>
<p class="topless"><a href="asyncio-queue.html"
title="previous chapter">Queues</a></p>
</div>
<div>
<h4>Next topic</h4>
<p class="topless"><a href="asyncio-eventloop.html"
title="next chapter">Event Loop</a></p>
</div>
<div role="note" aria-label="source link">
<h3>This Page</h3>
<ul class="this-page-menu">
<li><a href="../bugs.html">Report a Bug</a></li>
<li>
<a href="https://github.com/python/cpython/blob/main/Doc/library/asyncio-exceptions.rst"
rel="nofollow">Show Source
</a>
</li>
</ul>
</div>
</div>
<div id="sidebarbutton" title="Collapse sidebar">
<span>«</span>
</div>
</div>
<div class="clearer"></div>
</div>
<div class="related" role="navigation" aria-label="Related">
<h3>Navigation</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="../genindex.html" title="General Index"
>index</a></li>
<li class="right" >
<a href="../py-modindex.html" title="Python Module Index"
>modules</a> |</li>
<li class="right" >
<a href="asyncio-eventloop.html" title="Event Loop"
>next</a> |</li>
<li class="right" >
<a href="asyncio-queue.html" title="Queues"
>previous</a> |</li>
<li><img src="../_static/py.svg" alt="Python logo" style="vertical-align: middle; margin-top: -1px"/></li>
<li><a href="https://www.python.org/">Python</a> »</li>
<li class="switchers">
<div class="language_switcher_placeholder"></div>
<div class="version_switcher_placeholder"></div>
</li>
<li>
</li>
<li id="cpython-language-and-version">
<a href="../index.html">3.13.3 Documentation</a> »
</li>
<li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> »</li>
<li class="nav-item nav-item-2"><a href="ipc.html" >Networking and Interprocess Communication</a> »</li>
<li class="nav-item nav-item-3"><a href="asyncio.html" ><code class="xref py py-mod docutils literal notranslate"><span class="pre">asyncio</span></code> — Asynchronous I/O</a> »</li>
<li class="nav-item nav-item-this"><a href="">Exceptions</a></li>
<li class="right">
<div class="inline-search" role="search">
<form class="inline-search" action="../search.html" method="get">
<input placeholder="Quick search" aria-label="Quick search" type="search" name="q" id="search-box" />
<input type="submit" value="Go" />
</form>
</div>
|
</li>
<li class="right">
<label class="theme-selector-label">
Theme
<select class="theme-selector" oninput="activateTheme(this.value)">
<option value="auto" selected>Auto</option>
<option value="light">Light</option>
<option value="dark">Dark</option>
</select>
</label> |</li>
</ul>
</div>
<div class="footer">
©
<a href="../copyright.html">
Copyright
</a>
2001-2025, Python Software Foundation.
<br />
This page is licensed under the Python Software Foundation License Version 2.
<br />
Examples, recipes, and other code in the documentation are additionally licensed under the Zero Clause BSD License.
<br />
See <a href="/license.html">History and License</a> for more information.<br />
<br />
The Python Software Foundation is a non-profit corporation.
<a href="https://www.python.org/psf/donations/">Please donate.</a>
<br />
<br />
Last updated on Apr 08, 2025 (14:33 UTC).
<a href="/bugs.html">Found a bug</a>?
<br />
Created using <a href="https://www.sphinx-doc.org/">Sphinx</a> 8.2.3.
</div>
</body>
</html>