Fix “ignoring bigdecimal because its extensions are not built” error

Posted on Mon 15 October 2018 in articles

After upgrading to Mojave, I noticed that any brew commands starting spitting out this message:

~  brew update
Ignoring bigdecimal-1.3.4 because its extensions are not built. Try: gem pristine bigdecimal --version 1.3.4
Ignoring bigdecimal-1.3.4 because its extensions are not built. Try: gem pristine bigdecimal --version 1.3.4

This didn’t actually seem to affect anything. But it’s annoying, and I like to keep a good signal to noise ratio when I’m working. A little Googling led me to this fix

sudo /usr/bin/gem pristine bigdecimal --version 1.3.4

It appears it has something to do with fixing or updating the bigdecimal package that the system ruby interpreter is using (I don’t know ruby, so my take my explanation with a grain of salt), and running this command either updates or it cleans it up somehow. The trick is to use the system ruby, cause if you just run gem pristing bigdecimal -- version 1.3.4 like the error message tells you, it won’t fix it since it will be using brews ruby, which (for me) is located at /usr/local/bin.

Anyway, if you see this message for bigdecimal or any other gems it complains about, you can use this fix.