Helium ships with its own copies of gecko- and chromedriver. These binaries quickly become outdated. Previously, there was no easy way to "fix" Helium's webdrivers for your machine.
No longer. Now, Helium first attempts to use chromedriver and geckodriver from your PATH. This lets you install the versions of those drivers that work on your system.
The implementation is based on a PR by @TotallyNotChase. Thank you!