cannot install because Fatal Python error: initfsencoding: Unable to get the locale encoding

[themaddoctor]

Bug report

Bug summary

matplotlib-3.0.0 # python3 setup.py build
Fatal Python error: initfsencoding: Unable to get the locale encoding
File "/usr/lib/python2.7/encodings/init.py", line 123
raise CodecRegistryError,
^
SyntaxError: invalid syntax

Current thread 0x00007fbd592bd700 (most recent call first):
Aborted

Note: it's not my fault it is trying to use python2. Even
alias python=python3; python3 setup.py build
fails in the same way.

The only reason I am even trying to install in python 3 is that you no longer support P2, and
matplotlib 2.2 is broken:
python histogram_demo.py
/usr/lib/python2.7/site-packages/matplotlib/axes/_axes.py:6462: UserWarning: The 'normed' kwarg is deprecated, and has been replaced by the 'density' kwarg.
warnings.warn("The 'normed' kwarg is deprecated, and has been "
Traceback (most recent call last):
File "histogram_demo.py", line 10, in
n, bins, patches = plt.hist(x, 50, normed=1, facecolor='green', alpha=0.75)
File "/usr/lib/python2.7/site-packages/matplotlib/pyplot.py", line 3132, in hist
stacked=stacked, normed=normed, data=data, **kwargs)
File "/usr/lib/python2.7/site-packages/matplotlib/init.py", line 1855, in inner
return func(ax, *args, **kwargs)
File "/usr/lib/python2.7/site-packages/matplotlib/axes/_axes.py", line 6606, in hist
color=c, **{bottom_kwarg: bottom})
File "/usr/lib/python2.7/site-packages/matplotlib/init.py", line 1855, in inner
return func(ax, *args, **kwargs)
File "/usr/lib/python2.7/site-packages/matplotlib/axes/_axes.py", line 2233, in bar
np.atleast_1d(x), height, width, y, linewidth)
File "/usr/lib/python2.7/site-packages/numpy/lib/stride_tricks.py", line 119, in broadcast_arrays
zip(args, shapes, strides)]
File "/usr/lib/python2.7/site-packages/numpy/lib/stride_tricks.py", line 32, in as_strided
array.dtype = x.dtype
TypeError: Cannot change data-type for object array.

Code for reproduction

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Actual outcome

# If applicable, paste the console output here
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Expected outcome

Matplotlib version

• Operating system:
  linux
• Matplotlib version:
  3.0.0
• Matplotlib backend (print(matplotlib.get_backend())):
• Python version:
  3.7.0
• Jupyter version (if applicable):
• Other libraries:

[tacaswell]

Matplotlib 3.0 does not support python2.7. Do you have your environments crossed?

[themaddoctor]

You will notice that I invoked setup.py with python3

[themaddoctor]

OK, there was some environment variable set. Thank you for the tip.

[tacaswell]

Great, I am glad you got it sorted!

I did miss the python3 call, but saw the /usr/lib/python2.7/site-packages in the traceback!