<h3 dir="auto">Bug report</h3>
<p dir="auto"><strong>Bug summary</strong><br>
Can't use qt4agg, error reported below.</p>
<p dir="auto">Downgrade to matplotlib 3.1.3 solves the problem.</p>

<p dir="auto"><strong>Code for reproduction</strong></p>

<div class="highlight highlight-source-python notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="import matplotlib as mpl
mpl.use('qt4agg')"><pre class="notranslate"><span class="pl-k">import</span> <span class="pl-s1">matplotlib</span> <span class="pl-k">as</span> <span class="pl-s1">mpl</span>
<span class="pl-s1">mpl</span>.<span class="pl-en">use</span>(<span class="pl-s">'qt4agg'</span>)</pre></div>
<p dir="auto">Or, set it to Qt4Agg in <code class="notranslate">matplotlibrc</code> file.</p>
<p dir="auto"><strong>Actual outcome</strong></p>

<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="ImportError: cannot import name '_isdeleted' 
Failed to enable GUI event loop integration for 'qt5'"><pre class="notranslate"><code class="notranslate">ImportError: cannot import name '_isdeleted' 
Failed to enable GUI event loop integration for 'qt5'
</code></pre></div>


<p dir="auto"><strong>Matplotlib version</strong></p>

<ul dir="auto">
<li>Operating system: win 10 LTSC 2019</li>
<li>Matplotlib version: 3.2.1</li>
<li>Matplotlib backend (<code class="notranslate">print(matplotlib.get_backend())</code>): can only use TkAgg</li>
<li>Python version: 3.6</li>
</ul>
<h3 dir="auto">Bug report</h3>

<p dir="auto">After updating to latest version (3.2.1) I started getting this error:</p>
<div class="highlight highlight-source-python notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="# Paste your code here
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
&gt;&gt;&gt;from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
Traceback (most recent call last):
  File &quot;&lt;pyshell#0&gt;&quot;, line 1, in &lt;module&gt;
    from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
  File &quot;C:\Python37-32\lib\site-packages\matplotlib\backends\backend_qt4agg.py&quot;, line 5, in &lt;module&gt;
    from .backend_qt5agg import (
  File &quot;C:\Python37-32\lib\site-packages\matplotlib\backends\backend_qt5agg.py&quot;, line 11, in &lt;module&gt;
    from .backend_qt5 import (
  File &quot;C:\Python37-32\lib\site-packages\matplotlib\backends\backend_qt5.py&quot;, line 19, in &lt;module&gt;
    from .qt_compat import (
ImportError: cannot import name '_isdeleted' from 'matplotlib.backends.qt_compat' (C:\Python37-32\lib\site-packages\matplotlib\backends\qt_compat.py)
"><pre class="notranslate"><span class="pl-c"># Paste your code here</span>
<span class="pl-k">from</span> <span class="pl-s1">matplotlib</span>.<span class="pl-s1">backends</span>.<span class="pl-s1">backend_qt4agg</span> <span class="pl-k">import</span> <span class="pl-v">FigureCanvasQTAgg</span> <span class="pl-k">as</span> <span class="pl-v">FigureCanvas</span>
<span class="pl-c1">&gt;&gt;</span><span class="pl-c1">&gt;</span><span class="pl-k">from</span> <span class="pl-s1">matplotlib</span>.<span class="pl-s1">backends</span>.<span class="pl-s1">backend_qt4agg</span> <span class="pl-k">import</span> <span class="pl-v">FigureCanvasQTAgg</span> <span class="pl-k">as</span> <span class="pl-v">FigureCanvas</span>
<span class="pl-v">Traceback</span> (<span class="pl-s1">most</span> <span class="pl-s1">recent</span> <span class="pl-s1">call</span> <span class="pl-s1">last</span>):
  <span class="pl-v">File</span> <span class="pl-s">"&lt;pyshell#0&gt;"</span>, <span class="pl-s1">line</span> <span class="pl-c1">1</span>, <span class="pl-s1">in</span> <span class="pl-c1">&lt;</span><span class="pl-s1">module</span><span class="pl-c1">&gt;</span>
    <span class="pl-s1">from</span> <span class="pl-s1">matplotlib</span>.<span class="pl-s1">backends</span>.<span class="pl-s1">backend_qt4agg</span> <span class="pl-s1">import</span> <span class="pl-v">FigureCanvasQTAgg</span> <span class="pl-k">as</span> <span class="pl-v">FigureCanvas</span>
  <span class="pl-v">File</span> <span class="pl-s">"C:\Python37-32\lib\site-packages\matplotlib<span class="pl-cce">\b</span>ackends<span class="pl-cce">\b</span>ackend_qt4agg.py"</span>, <span class="pl-s1">line</span> <span class="pl-c1">5</span>, <span class="pl-s1">in</span> <span class="pl-c1">&lt;</span><span class="pl-s1">module</span><span class="pl-c1">&gt;</span>
    <span class="pl-s1">from</span> .<span class="pl-s1">backend_qt5agg</span> <span class="pl-s1">import</span> (
  <span class="pl-v">File</span> <span class="pl-s">"C:\Python37-32\lib\site-packages\matplotlib<span class="pl-cce">\b</span>ackends<span class="pl-cce">\b</span>ackend_qt5agg.py"</span>, <span class="pl-s1">line</span> <span class="pl-c1">11</span>, <span class="pl-s1">in</span> <span class="pl-c1">&lt;</span><span class="pl-s1">module</span><span class="pl-c1">&gt;</span>
    <span class="pl-s1">from</span> .<span class="pl-s1">backend_qt5</span> <span class="pl-s1">import</span> (
  <span class="pl-v">File</span> <span class="pl-s">"C:\Python37-32\lib\site-packages\matplotlib<span class="pl-cce">\b</span>ackends<span class="pl-cce">\b</span>ackend_qt5.py"</span>, <span class="pl-s1">line</span> <span class="pl-c1">19</span>, <span class="pl-s1">in</span> <span class="pl-c1">&lt;</span><span class="pl-s1">module</span><span class="pl-c1">&gt;</span>
    <span class="pl-s1">from</span> .<span class="pl-s1">qt_compat</span> <span class="pl-s1">import</span> (
<span class="pl-v">ImportError</span>: <span class="pl-s1">cannot</span> <span class="pl-k">import</span> <span class="pl-s1">name</span> <span class="pl-s">'_isdeleted'</span> <span class="pl-s1">from</span> <span class="pl-s">'matplotlib.backends.qt_compat'</span> (<span class="pl-v">C</span>:\P<span class="pl-s1">ython37</span><span class="pl-c1">-</span><span class="pl-c1">32</span>\l<span class="pl-s1">ib</span>\s<span class="pl-s1">ite</span><span class="pl-c1">-</span><span class="pl-s1">packages</span>\m<span class="pl-s1">atplotlib</span>\b<span class="pl-s1">ackends</span>\q<span class="pl-s1">t_compat</span>.<span class="pl-s1">py</span>)</pre></div>



<p dir="auto"><strong>Matplotlib version</strong></p>

<ul dir="auto">
<li>Operating system: Windows 10</li>
<li>Matplotlib version: 3.2.1</li>
<li>Matplotlib backend (<code class="notranslate">print(matplotlib.get_backend())</code>):TkAgg</li>
<li>Python version:3.7.6 (32Bit)</li>
<li>Jupyter version (if applicable):</li>
<li>Other libraries:<br>
altgraph          0.17<br>
astroid           2.3.3<br>
colorama          0.4.3<br>
cx-Freeze         6.1<br>
cycler            0.10.0<br>
future            0.18.2<br>
isort             4.3.21<br>
joblib            0.14.1<br>
kiwisolver        1.1.0<br>
lazy-object-proxy 1.4.3<br>
matplotlib        3.2.1<br>
mccabe            0.6.1<br>
mpmath            1.1.0<br>
numpy             1.18.2+mkl<br>
pandas            1.0.3<br>
pefile            2019.4.18<br>
pip               20.0.2<br>
psutil            5.7.0<br>
PyInstaller       4.0.dev0+d08a42c612<br>
pylint            2.4.4<br>
pyparsing         2.4.6<br>
PyQt4             4.11.4<br>
PyQt5-sip         12.7.1<br>
python-dateutil   2.8.1<br>
pytz              2019.3<br>
pywin32-ctypes    0.2.0<br>
scikit-learn      0.22.2.post1<br>
scipy             1.4.1<br>
setuptools        46.0.0<br>
six               1.14.0<br>
tailer            0.4.1<br>
typed-ast         1.4.1<br>
wrapt             1.12.1<br>
xlrd              1.2.0<br>
XlsxWriter        1.2.8</li>
</ul>