# Backend or Zlib problem with PyPlot / Matplotlib

**URL:** <https://discourse.julialang.org/t/backend-or-zlib-problem-with-pyplot-matplotlib/2685>\
**Category:** General Usage\
**Created:** [March 15, 2017, 7:15pm UTC](https://discourse.julialang.org/t/backend-or-zlib-problem-with-pyplot-matplotlib/2685 "2017-03-15T19:15:52Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![Ralph\_Smith](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ralph_smith/32/10344_2.png) [@Ralph\_Smith](https://discourse.julialang.org/u/Ralph_Smith)\
**Post date:** [March 16, 2017, 1:48am UTC](https://discourse.julialang.org/t/backend-or-zlib-problem-with-pyplot-matplotlib/2685/2 "2017-03-16T01:48:02Z")

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As @stevengj mentioned in [a similar thread](https://discourse.julialang.org/t/no-working-gui-backend-found-for-matplotlib/2479)

> [@No working GUI backend found for matplotlib](https://discourse.julialang.org/t/no-working-gui-backend-found-for-matplotlib/2479/9):
>
> See [error loading ZLIB (wrong libz library being linked) · Issue #151 · JuliaPy/PyPlot.jl · GitHub](https://github.com/JuliaPy/PyPlot.jl/issues/151) … the problem is that it is finding the wrong libz.so library

The Zlib project makes a good effort at backwards compatibility (using version scripts, if anyone is interested) so it should be safe to force Julia to use a newer version. Does PyPlot work for you if you start Julia as follows?

```shell
LD_PRELOAD=${HOME}/.julia/v0.5/Conda/deps/usr/lib/libz.so julia

```

You can also try setting LD\_LIBRARY\_PATH to the Conda lib directory, but that exposes your Julia process to other crocodiles in the Python dependency swamp.

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