Bundle update can be the cause of a splitting headache. A lesser
known fact is that when you run
bundle update GEMNAME bundler will
actually update GEMNAME and all of GEMNAME's dependencies. And this of
course can lead to a much higher chance of conflicts.
Checkout the video to see what I mean:
Give this a try next time you need to 'update' a gem. For more detail, checkout this great explanation and more tips: https://makandracards.com/makandra/13885-how-to-update-a-single-gem-conservatively