import matplotlib.pyplot gives ImportError: dlopen(...) Library not loaded libpng15.15.dylib

Question

Importing pyplot gives an error:

In [1]: import matplotlib
In [2]: import matplotlib.pyplot as plt
ImportError                               Traceback (most recent call last)
<ipython-input-2-eff513f636fd> in <module>()
----> 1 import matplotlib.pyplot as plt
/Users/r8t/anaconda/lib/python2.7/site-packages/matplotlib/pyplot.py in <module>()
     25
     26 import matplotlib
---> 27 import matplotlib.colorbar
     28 from matplotlib import style
     29 from matplotlib import _pylab_helpers, interactive

/Users/r8t/anaconda/lib/python2.7/site-packages/matplotlib/colorbar.py in <module>()
     32 import matplotlib.artist as martist
     33 import matplotlib.cbook as cbook
---> 34 import matplotlib.collections as collections
     35 import matplotlib.colors as colors
     36 import matplotlib.contour as contour
/Users/r8t/anaconda/lib/python2.7/site-packages/matplotlib/collections.py in <module>()
     25 import matplotlib.artist as artist
     26 from matplotlib.artist import allow_rasterization
---> 27 import matplotlib.backend_bases as backend_bases
     28 import matplotlib.path as mpath
     29 from matplotlib import _path
/Users/r8t/anaconda/lib/python2.7/site-packages/matplotlib/backend_bases.py in <module>()
     54
     55 import matplotlib.tight_bbox as tight_bbox
---> 56 import matplotlib.textpath as textpath
     57 from matplotlib.path import Path
     58 from matplotlib.cbook import mplDeprecation
/Users/r8t/anaconda/lib/python2.7/site-packages/matplotlib/textpath.py in <module>()
     20 from matplotlib.ft2font import FT2Font, KERNING_DEFAULT, LOAD_NO_HINTING
     21 from matplotlib.ft2font import LOAD_TARGET_LIGHT
 ---> 22 from matplotlib.mathtext import MathTextParser
     23 import matplotlib.dviread as dviread
     24 from matplotlib.font_manager import FontProperties

/Users/r8t/anaconda/lib/python2.7/site-packages/matplotlib/mathtext.py in <module>()
     61
     62 import matplotlib.colors as mcolors
---> 63 import matplotlib._png as _png
     64 ####################
     65
 ImportError: dlopen(/Users/r8t/anaconda/lib/python2.7/site-packages/matplotlib/_png.so, 2): Library   not loaded: libpng15.15.dylib
  Referenced from: /Users/r8t/anaconda/lib/python2.7/site-packages/matplotlib/_png.so
  Reason: image not found

I've looked at Error importing matplotlib.pyplot which suggests deleting the matplotlib folder. I tried it and it didn't work. This also doesn't have a solution, but I think is related: Python: py2app "ImportError: dlopen(): Library not loaded"

Also i made sure I have libpng installed (via brew). Thanks,

I also tried uninstalling matplot lib via pip, then brew reinstalling libpng and freetype, then pip installing matplotlib and I get the same error... ugh. — travelingbones, Dec 17 '14 at 21:51

score 6 · Accepted Answer · answered Mar 31 '15 at 05:49

(sorry I can not comment yet.. so here's a new post)

I had the same problem when installing another library (spynner): dlopen(…) Library not loaded libpng15.15.dylib

I tried a similar method to @travelingbones's answer, and just wanted to add some notes for future readers:

DYLD_LIBRARY_PATH should contain directories, not files. E.g.,

export DYLD_LIBRARY_PATH=/Users/xxx/anaconda/lib:$DYLD_LIBRARY_PATH

and not

export DYLD_LIBRARY_PATH=/Users/xxx/anaconda/lib/libpng15.15.dylib:$DYLD_LIBRARY_PATH

The error /usr/X11/lib/libpng15.15.dylib/libpng15.15.dylib: stat() failed with errno=20 is caused by the wrong DYLD_LIBRARY_PATH, since file path /usr/X11/lib/libpng15.15.dylib/libpng15.15.dylib does not exist (notice the double libpng15.15.dylib in the file path).

After I had set the new DYLD_LIBRARY_PATH, I found my matplotlib was messed up, with the following error:

ImportError: dlopen(/Users/shenggao/anaconda/lib/python2.7/site-packages/matplotlib/backends/_macosx.so, 2): Symbol not found: __cg_jpeg_resync_to_restart
Referenced from: /System/Library/Frameworks/ImageIO.framework/Versions/A/ImageIO
Expected in: /Users/shenggao/anaconda/lib/libjpeg.8.dylib in /System/Library/Frameworks/ImageIO.framework/Versions/A/ImageIO

To solve this problem, I changed DYLD_LIBRARY_PATH back to the old value (i.e., empty), and added the libpng path to DYLD_FALLBACK_LIBRARY_PATH like this:

export DYLD_FALLBACK_LIBRARY_PATH=/Users/shenggao/anaconda/lib:$DYLD_FALLBACK_LIBRARY_PATH

Finally matplotlib and my new library worked like a charm!

Cool! Thanks for sharing. I since then reimaged my mac, and reinstalled everything python using brew and pip. Everything has been working fine since. I supposed that's another solution if you're willing to wipe your machine and start with a fresh OS. — travelingbones, Apr 02 '15 at 03:05

score 1 · Answer 2 · edited May 23 '17 at 12:16

I followed these directions and got a different error that's fixable: First I checked what's in that path:

macair93278:~ r8t$ echo $DYLD_LIBRARY_PATH

(empty)

Next to locate the file I need (libpng15.15.dylib):

macair93278:~ r8t$ locate libpng15.15.dylib
/Applications/KeePassX.app/Contents/MacOS/libpng15.15.dylib
/Users/r8t/anaconda/lib/libpng15.15.dylib
/Users/r8t/anaconda/pkgs/libpng-1.5.13-1/lib/libpng15.15.dylib
/usr/X11/lib/libpng15.15.dylib

Now I appended the bottom three to the path and checked the path:

macair93278:~ r8t$ echo $DYLD_LIBRARY_PATH  
/usr/X11/lib/libpng15.15.dylib:/Users/r8t/anaconda/pkgs/libpng-1.5.13-1/lib/libpng15.15.dylib:/Users/r8t/anaconda/lib/libpng15.15.dylib

ok, so now the test,

macair93278:~ r8t$ ipython

In [1]: import matplotlib

In [2]: from matplotlib import pyplot
…(bunch of output)
ImportError: dlopen(/Users/r8t/anaconda/lib/python2.7/site-packages/matplotlib/_png.so, 2): Library not loaded: libpng15.15.dylib
Referenced from: /Users/r8t/anaconda/lib/python2.7/site-packages/matplotlib/_png.so
Reason: no suitable image found. Did find:
/usr/X11/lib/libpng15.15.dylib/libpng15.15.dylib: stat() failed with errno=20
/Users/r8t/anaconda/pkgs/libpng-1.5.13-1/lib/libpng15.15.dylib/libpng15.15.dylib: stat() failed with errno=20
/Users/r8t/anaconda/lib/libpng15.15.dylib/libpng15.15.dylib: stat() failed with errno=20

A different error! progress! Now following this page I ran the brew link, then unlink it didn't fix it, but it pointed me to the fact that pyplot is looking for libpng15.15.dylib in usr/local/lib but they aren' there:

macair93278:~ r8t$ cd ../usr/local/lib
macair93278:lib r8t$ ls *png*
libpng.a libpng16.16.dylib libpng16.dylib
libpng.dylib libpng16.a

So copy them in there:

macair93278:~ r8t$ cp ../anaconda/lib/*png* /usr/local/lib
macair93278:~ r8t$ cd /usr/local/lib

The test:

In [1]: import matplotlib 

In [2]: from matplotlib import pyplot
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/r8t/anaconda/lib/python2.7/site-packages/matplotlib/pyplot.py", line 109, in <module>
_backend_mod, new_figure_manager, draw_if_interactive, _show = pylab_setup()
  File "/Users/r8t/anaconda/lib/python2.7/site-packages/matplotlib/backends/__init__.py", line 32, in pylab_setup
    globals(),locals(),[backend_name],0)
  File "/Users/r8t/anaconda/lib/python2.7/site-packages/matplotlib/backends/backend_macosx.py", line 24, in <module>
    from matplotlib.backends import _macosx
RuntimeError: Python is not installed as a framework. The Mac OS X backend will not be able to function correctly if Python is not installed as a framework. See the Python documentation for more information on installing Python as a framework on Mac OS X. Please either reinstall Python as a framework, or try one of the other backends.

And we've reduced the problem to this (solved) one: problem w/ mac os backend

import matplotlib.pyplot gives ImportError: dlopen(...) Library not loaded libpng15.15.dylib

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