Kernkraft installation and instructions for use


If someone could please help me

install Kernkraft plugin for glyphs app

find instructions on how to use it to kern my font… i would be much obliged

my google searches have been of no help



Have you tried this Kernkraft Wiki?
It could get you started. However, I wrote that years ago and never found time to work on it since then.
Let me know if you have more questions.

hi mark

thanks for getting back to me…

i worked it out.

you need to put it in the folder scripts folder (scripts folder)

than under windows menu,go to plugins menu and install

then go to “glyph”, and scroll down… there it is!

as you can see i am a total non coder… non techie.

but i have it installed now, am using it… its great.

i really needed to know how to kern all the fonts i have designed, as i am teaching others to use glyphs and this was a total stumbling block.

Not sure about that. I expected you just install it via the Plugin Manager. No Scripts Folder needed.

You don’t need Kernkraft at all to kern fonts. It just helps you along the way, especially with large glyph sets.

hi again Mark


i know you don’t need it. but it does make things much faster. i really like it. now my font finally has all the tricky pairings kerned… I had a lot of trouble with metrics machine … as i am busy, and need to be across alot of areas… so need solutions that are easy to implement.

I think you should charge for it… metrics machine cost me $100 and i can’t even use it!


Thank you for the motivational reply, I really appreciate it.

Charging is a topic of its own, I am still happy to provide free tools whenever they didn’t cost my too much time and basically were developed along my personal workflows. Recently my tools got more and more complex and need constant updating along with GlyphsApp updates and user requests, so those happen to be commercial plugins. Kernkraft in particular has been commissioned and funded by @bBox_Type back then to be open source. :slight_smile:

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Hi Mark, I’m having a challenge getting Kernkraft to appear. I have installed the plugin via the Plugin Manager.

However when I click on the Glyph menu, Kernkraft and Glyph does not appear.

I have already explored manually installing Vanilla and manually installing Kernkraft but still not having any luck. Also receive this error message each time I reopen Glyphs:
“The Plugin Kernkraft.glyphsPlugin has caused a crash. Please update it by opening the Plugin Manager or re-downloading it from the original source.”

Thanks for your help.

Which exact OS and app version?

Glyphs app version: 2.6.5
macOS: Catalina Version 10.15.6

First: Try the latest beta please. Go to Glyphs > Preferences > Updates, activate both checkboxes and press the Update button.

That dialog should also provide you with the spot inside the code (line number, some Python code) that caused the trouble. Can you post that too? (Perhaps after updating to the 2.6.6 beta.)

Thanks for the speedy reply! I updated the version to 2.6.6 beta and now Kernkraft is loading as expected, appearing under Glyph menu.


Glad to read that you figured it out and thanks Rainer for jumping in so quickly. :raised_hands:

Unfortunately Kernkraft is not working for me either. I’m on Catalina 10.15.6, Glyphs 2.6.6.
I tried installing via Plugin Manager and manually via Scripts Folder. Both didn’t work. I also tried Tim Ahrens explanation about rejected plugins. Didn’t work neither.
This is the message I get when opening Glyphs after I installed Kernkraft via Plugin Manager:

File “~/Library/Application Support/Glyphs/Repositories/Kernkraft/Kernkraft.glyphsPlugin/Contents/Resources/”, line 15, in
import KernKraftModule as KKM

File “~/Library/Application Support/Glyphs/Repositories/Kernkraft/Kernkraft.glyphsPlugin/Contents/Resources/”, line 37, in
from vanilla import *

File “~/Library/Application Support/Glyphs/Scripts/vanilla/”, line 3, in
from vanilla.vanillaBrowser import ObjectBrowser

File “~/Library/Application Support/Glyphs/Scripts/vanilla/”, line 7, in
from objc import python_method

ImportError: cannot import name python_method

App:2.6.6-1348 Plugin:4-2.0.0

Any help would be highly appreciated!

Did you install the modules? Preferences > Addons > Modules > Install.

Now I did! :man_facepalming:
Thanks again Rainer!

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I’m on Glyphs 2.6.6 (1351) and I’m getting this message when clicking the Open Tab button:

    The Plugin Kernkraft.glyphsPlugin has caused a crash. Please update it by opening the Plugin Manager or re-downloading it from the original source.

Traceback (most recent call last):

  File "~/Library/Application Support/Glyphs/Scripts/vanilla/", line 505, in action_

  File "~/Library/Application Support/Glyphs/Repositories/Kernkraft/Kernkraft.glyphsPlugin/Contents/Resources/", line 1324, in submitButtonCallback
    for error in self.parent.errorCollector:

AttributeError: 'KernKraft' object has no attribute 'errorCollector'

App:2.6.6-1351 Plugin:(null)-(null)

I have all modules installed through Preferences: Addons

full of crash reports for me too. I’m on Mojave 10.14.6, All modules installed.

The last error message is:
The Plugin Kernkraft.glyphsPlugin has caused a crash. Please update it by opening the Plugin Manager or re-downloading it from the original source.

Traceback (most recent call last):

File "", line 506, in action_

File "", line 1325, in submitButtonCallback

AttributeError: 'PreferenceWindow' object has no attribute 'errorCollector'

App:3.0.2-3053 Plugin:(null)-(null)

I fixed something, that was a hard one to debug.
Looks like there was a check missing, if a selected Layer exists. If it didn’t, the window was not properly initialised and hence it thought there is no PreferenceWindow.

Hope it works now. Let me know if not, and please @ me, otherwise I will only see reports here by accident.

thanks @Mark :slight_smile:
@GeorgSeifert , plugins are updated automatically with no message in Glyphs 3? I didn’t see any since I’m using v3