NoMethodError: undefined method `bindings' for java.lang.NullPointerException - ruby-on-rails

Question

we're working on a ruby on rails (4.2.8) application which is running on jruby-1.7.25. It really is time to update this mummy to the latest version 9.1.7.0. We did that and for most of my colleagues it works out fine. But - guess what - not for me. Before posting my question here, I made sure that:
I have the same setup
Same DB content
The exactly same code
as the others, but I still get that stupid error which is
java.lang.NullPointerException and that's really all, the app is spitting out on any request.
I was digging for the last hours and found out, that the real issue is getting lost in the depth of logging. Finally I found, that I will see the real cause if I add a puts in the file vendor/jruby/2.3.0/gems/actionpack-4.2.8/lib/action_dispatch/middleware/show_exceptions.rb like:
class ShowExceptions
FAILSAFE_RESPONSE = [500, { 'Content-Type' => 'text/plain' },
["500 Internal Server Error\n" \
"If you are the administrator of this website, then please read this web " \
"application's log file and/or the web server's log file to find out what " \
"went wrong."]]
def initialize(app, exceptions_app)
#app = app
#exceptions_app = exceptions_app
end
def call(env)
#app.call(env)
rescue Exception => exception
puts "EXCEPTION: #{exception.inspect}\n#app: #{#app.inspect}\nENV: #{env.inspect}"
if env['action_dispatch.show_exceptions'] == false
raise exception
else
render_exception(env, exception)
end
end
The output is:
EXCEPTION: #<NoMethodError: undefined method `bindings' for java.lang.NullPointerException:Java::JavaLang::NullPointerException
#app and env print out kilobytes of data which probably do not help. Honestly, I'm kind of stuck here. How can it work on other machines while it fails on mine? Has anyone of you had a similar issue or any idea what causes this trouble?
Ah, some version infos
Puma: * Version 3.7.1 (jruby 9.1.7.0 - ruby 2.3.1), codename: Snowy Sagebrush
jruby: jruby 9.1.7.0 (2.3.1) 2017-01-11 68056ae Java HotSpot(TM) 64-Bit Server VM 24.79-b02 on 1.7.0_79-b15 +jit [darwin-x86_64]
java: java version "1.7.0_79"
Java(TM) SE Runtime Environment (build 1.7.0_79-b15)
Java HotSpot(TM) 64-Bit Server VM (build 24.79-b02, mixed mode)
Mac OSX: 10.12.3 (16D32)
Thanks for any hints!