I started seeing this error: LoadError: cannot load such file -- pdf417/pdf417.

In case anyone else finds this, it was because ext/pdf417/extconf.rb contained create_makefile(extension_name) (which resolves to create_makefile('pdf417').) This now needs to be create_makefile('pdf417/pdf417') in order for require('pdf417/pdf417') to work properly.

I fixed this issue in our fork: https://github.com/DocSpring/pdf417