I love using G'MIC in Krita, but Krita 4.0.0 and 4.0.1 crash when I use Filter/Start G'MIC-QT . (it works perfectly in GIMP).

I've done as explained in https://docs.krita.org/GMIC_filter_plugin, and tried the Ubuntu Xenial, Artful and Debian gmic_krita_qt plugins from http://gmic.eu/.
I installed libgmic1 package. It did not work.
I tried the Debian Jessie and Stretch plugins, and others (just in case). That did not work either.
All the plugins have permission to run as executable.

This is my Linux distro: "Linux Mint 17.3 Rosa" VM40B 4.4.0-119-generic #143~14.04.1-Ubuntu SMP Mon Apr 2 18:04:36 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

I had success using the gmic_krita appimage that you can find here (at the top above the krita pre-alpha link):

https://binary-factory.kde.org/job/Krit ... age_Build/

Download it, give it executable permissions, put it in a sensible place then tell krita where to find it in Settings -> Configure Krita
Please let us know if it works for you.