<p dir="auto">Firstly, I installed Xcode command line developer tools. Then, I installed numpy via pip3. When I try to run python code, I give an error. In previous version (macOS Mojave) everything was okay.</p>
<h3 dir="auto">Reproducing code example:</h3>
<div class="highlight highlight-source-python notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="import numpy as np"><pre class="notranslate"><span class="pl-k">import</span> <span class="pl-s1">numpy</span> <span class="pl-k">as</span> <span class="pl-s1">np</span></pre></div>
<h3 dir="auto">Error message:</h3>
<p dir="auto">Python(3853,0x112ed8e00) malloc: can't allocate region<br>
:*** mach_vm_map(size=18446744072247156736, flags: 100) failed (error code=3)<br>
Python(3853,0x112ed8e00) malloc: *** set a breakpoint in malloc_error_break to debug<br>
init_dgelsd failed init<br>
Traceback (most recent call last):<br>
File "", line 1, in <br>
File "/Users/martin/Library/Python/3.8/lib/python/site-packages/numpy/<strong>init</strong>.py", line 286, in <br>
raise RuntimeError(msg)<br>
RuntimeError: Polyfit sanity test emitted a warning, most likely due to using a buggy Accelerate backend. If you compiled yourself, see site.cfg.example for information. Otherwise report this to the vendor that provided NumPy.<br>
RankWarning: Polyfit may be poorly conditioned</p>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/74611856/99424571-22799980-2902-11eb-8bfc-0b43eaf1cc88.png"><img width="1312" alt="Snímka obrazovky 2020-11-17 o 18 24 15" src="https://user-images.githubusercontent.com/74611856/99424571-22799980-2902-11eb-8bfc-0b43eaf1cc88.png" style="max-width: 100%;"></a></p>
<h3 dir="auto">NumPy/Python version information:</h3>
<p dir="auto">Numpy: 1.19.4<br>
Python: 3.8.2</p>
<h3 dir="auto">Reproducing code example:</h3>
<p dir="auto">Install Pandas with PIP after a clean install of macOS Big Sur and Python3.9 via Homebrew.</p>
<div class="highlight highlight-source-python notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="pip install pandas
pip3 install pandas
pip3 install pandas --no-build-isolation --no-cache-dir
sudo pip3 install pandas --no-cache-dir"><pre class="notranslate"><span class="pl-s1">pip</span> <span class="pl-s1">install</span> <span class="pl-s1">pandas</span>
<span class="pl-s1">pip3</span> <span class="pl-s1">install</span> <span class="pl-s1">pandas</span>
<span class="pl-s1">pip3</span> <span class="pl-s1">install</span> <span class="pl-s1">pandas</span> <span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-s1">no</span><span class="pl-c1">-</span><span class="pl-s1">build</span><span class="pl-c1">-</span><span class="pl-s1">isolation</span> <span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-s1">no</span><span class="pl-c1">-</span><span class="pl-s1">cache</span><span class="pl-c1">-</span><span class="pl-s1">dir</span>
<span class="pl-s1">sudo</span> <span class="pl-s1">pip3</span> <span class="pl-s1">install</span> <span class="pl-s1">pandas</span> <span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-s1">no</span><span class="pl-c1">-</span><span class="pl-s1">cache</span><span class="pl-c1">-</span><span class="pl-s1">dir</span></pre></div>
<p dir="auto">These are the only packages actually installed:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="Package    Version
---------- -------
pip        20.2.4
setuptools 50.3.2
wheel      0.35.1"><pre class="notranslate"><code class="notranslate">Package    Version
---------- -------
pip        20.2.4
setuptools 50.3.2
wheel      0.35.1
</code></pre></div>
<h3 dir="auto">Error message:</h3>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="  Getting requirements to build wheel ... error
  ERROR: Command errored out with exit status 1:
   command: /usr/local/opt/python@3.9/bin/python3.9 /usr/local/lib/python3.9/site-packages/pip/_vendor/pep517/_in_process.py get_requires_for_build_wheel /var/folders/zv/0q58rjv549bd4qjdqlrwlvl40000gn/T/tmpzr3sthd6
       cwd: /private/var/folders/zv/0q58rjv549bd4qjdqlrwlvl40000gn/T/pip-install-pvlaq6iq/pandas
  Complete output (23 lines):
  init_dgelsd failed init
  Traceback (most recent call last):
    File &quot;/usr/local/lib/python3.9/site-packages/pip/_vendor/pep517/_in_process.py&quot;, line 280, in &lt;module&gt;
      main()
    File &quot;/usr/local/lib/python3.9/site-packages/pip/_vendor/pep517/_in_process.py&quot;, line 263, in main
      json_out['return_val'] = hook(**hook_input['kwargs'])
    File &quot;/usr/local/lib/python3.9/site-packages/pip/_vendor/pep517/_in_process.py&quot;, line 114, in get_requires_for_build_wheel
      return hook(config_settings)
    File &quot;/private/var/folders/zv/0q58rjv549bd4qjdqlrwlvl40000gn/T/pip-build-env-ly4c8n5_/overlay/lib/python3.9/site-packages/setuptools/build_meta.py&quot;, line 149, in get_requires_for_build_wheel
      return self._get_build_requires(
    File &quot;/private/var/folders/zv/0q58rjv549bd4qjdqlrwlvl40000gn/T/pip-build-env-ly4c8n5_/overlay/lib/python3.9/site-packages/setuptools/build_meta.py&quot;, line 130, in _get_build_requires
      self.run_setup()
    File &quot;/private/var/folders/zv/0q58rjv549bd4qjdqlrwlvl40000gn/T/pip-build-env-ly4c8n5_/overlay/lib/python3.9/site-packages/setuptools/build_meta.py&quot;, line 253, in run_setup
      super(_BuildMetaLegacyBackend,
    File &quot;/private/var/folders/zv/0q58rjv549bd4qjdqlrwlvl40000gn/T/pip-build-env-ly4c8n5_/overlay/lib/python3.9/site-packages/setuptools/build_meta.py&quot;, line 145, in run_setup
      exec(compile(code, __file__, 'exec'), locals())
    File &quot;setup.py&quot;, line 488, in &lt;module&gt;
      import numpy as np
    File &quot;/private/var/folders/zv/0q58rjv549bd4qjdqlrwlvl40000gn/T/pip-build-env-ly4c8n5_/overlay/lib/python3.9/site-packages/numpy/__init__.py&quot;, line 286, in &lt;module&gt;
      raise RuntimeError(msg)
  RuntimeError: Polyfit sanity test emitted a warning, most likely due to using a buggy Accelerate backend. If you compiled yourself, see site.cfg.example for information. Otherwise report this to the vendor that provided NumPy.
  RankWarning: Polyfit may be poorly conditioned

  ----------------------------------------
ERROR: Command errored out with exit status 1: /usr/local/opt/python@3.9/bin/python3.9 /usr/local/lib/python3.9/site-packages/pip/_vendor/pep517/_in_process.py get_requires_for_build_wheel /var/folders/zv/0q58rjv549bd4qjdqlrwlvl40000gn/T/tmpzr3sthd6 Check the logs for full command output."><pre class="notranslate"><code class="notranslate">  Getting requirements to build wheel ... error
  ERROR: Command errored out with exit status 1:
   command: /usr/local/opt/python@3.9/bin/python3.9 /usr/local/lib/python3.9/site-packages/pip/_vendor/pep517/_in_process.py get_requires_for_build_wheel /var/folders/zv/0q58rjv549bd4qjdqlrwlvl40000gn/T/tmpzr3sthd6
       cwd: /private/var/folders/zv/0q58rjv549bd4qjdqlrwlvl40000gn/T/pip-install-pvlaq6iq/pandas
  Complete output (23 lines):
  init_dgelsd failed init
  Traceback (most recent call last):
    File "/usr/local/lib/python3.9/site-packages/pip/_vendor/pep517/_in_process.py", line 280, in &lt;module&gt;
      main()
    File "/usr/local/lib/python3.9/site-packages/pip/_vendor/pep517/_in_process.py", line 263, in main
      json_out['return_val'] = hook(**hook_input['kwargs'])
    File "/usr/local/lib/python3.9/site-packages/pip/_vendor/pep517/_in_process.py", line 114, in get_requires_for_build_wheel
      return hook(config_settings)
    File "/private/var/folders/zv/0q58rjv549bd4qjdqlrwlvl40000gn/T/pip-build-env-ly4c8n5_/overlay/lib/python3.9/site-packages/setuptools/build_meta.py", line 149, in get_requires_for_build_wheel
      return self._get_build_requires(
    File "/private/var/folders/zv/0q58rjv549bd4qjdqlrwlvl40000gn/T/pip-build-env-ly4c8n5_/overlay/lib/python3.9/site-packages/setuptools/build_meta.py", line 130, in _get_build_requires
      self.run_setup()
    File "/private/var/folders/zv/0q58rjv549bd4qjdqlrwlvl40000gn/T/pip-build-env-ly4c8n5_/overlay/lib/python3.9/site-packages/setuptools/build_meta.py", line 253, in run_setup
      super(_BuildMetaLegacyBackend,
    File "/private/var/folders/zv/0q58rjv549bd4qjdqlrwlvl40000gn/T/pip-build-env-ly4c8n5_/overlay/lib/python3.9/site-packages/setuptools/build_meta.py", line 145, in run_setup
      exec(compile(code, __file__, 'exec'), locals())
    File "setup.py", line 488, in &lt;module&gt;
      import numpy as np
    File "/private/var/folders/zv/0q58rjv549bd4qjdqlrwlvl40000gn/T/pip-build-env-ly4c8n5_/overlay/lib/python3.9/site-packages/numpy/__init__.py", line 286, in &lt;module&gt;
      raise RuntimeError(msg)
  RuntimeError: Polyfit sanity test emitted a warning, most likely due to using a buggy Accelerate backend. If you compiled yourself, see site.cfg.example for information. Otherwise report this to the vendor that provided NumPy.
  RankWarning: Polyfit may be poorly conditioned

  ----------------------------------------
ERROR: Command errored out with exit status 1: /usr/local/opt/python@3.9/bin/python3.9 /usr/local/lib/python3.9/site-packages/pip/_vendor/pep517/_in_process.py get_requires_for_build_wheel /var/folders/zv/0q58rjv549bd4qjdqlrwlvl40000gn/T/tmpzr3sthd6 Check the logs for full command output.
</code></pre></div>
<h3 dir="auto">NumPy/Python version information:</h3>
<p dir="auto">I have also installed NumPy first (numpy 1.19.4) still getting the same error.<br>
I have opened the following issues and in both of them they said that it's a Numpy error: <a href="https://github.com/pandas-dev/pandas/issues/37880" data-hovercard-type="issue" data-hovercard-url="/pandas-dev/pandas/issues/37880/hovercard">Pandas#37880</a> and <a href="https://github.com/pypa/pip/issues/9138" data-hovercard-type="issue" data-hovercard-url="/pypa/pip/issues/9138/hovercard">Pip#9138</a></p>