Rails failing on Tomcat with JRuby 9.1.12

[F2 Andy]

I am having problems getting JRuby 9.1.12 to run my Rails project. I was previously on 9.1.2, and that works fine. All I have done is updated JRuby, and now it fails.

To investigate, I created a test project, first using JRuby 9.1.2:

rails new testy --database postgresql
cd testy
rails g scaffold Location name:string

Location is a table in an existing database, so quicker for testing. I deleted the migration, copied across database.yml from my project, and edited secret.yml so it uses the same key as the tests. Then:

rake test
warble

Then I put the .war into Tomcat and it works fine. So then JRuby 9.1.12:
 

gem uninstall -v 9.1.2 jruby-jars
gem install -v 9.1.12 jruby-jars
warble

I stop Tomcat, delete the old files, and put this new war in. Now I see this when going to a page in testy:
 

org.jruby.rack.RackInitializationException: java.lang.NullPointerException
    at org.jruby.rack.RackInitializationException.wrap(RackInitializationException.java:31)
    at org.jruby.rack.RackApplicationFactoryDecorator.init(RackApplicationFactoryDecorator.java:104)
    at org.jruby.rack.RackServletContextListener.contextInitialized(RackServletContextListener.java:50)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4853)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5314)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:753)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:729)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:717)
    at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:976)
    at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1853)
    at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
    at java.util.concurrent.FutureTask.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException
    at java.lang.String.getBytes(Unknown Source)
    at org.jruby.ast.SymbolNode.<init>(SymbolNode.java:54)
    at org.jruby.parser.ParserSupport.asSymbol(ParserSupport.java:975)
    at org.jruby.parser.RubyParser$379.execute(RubyParser.java:4286)
    at org.jruby.parser.RubyParser.yyparse(RubyParser.java:1677)
    at org.jruby.parser.RubyParser.yyparse(RubyParser.java:1568)
    at org.jruby.parser.RubyParser.parse(RubyParser.java:5365)
    at org.jruby.parser.Parser.parse(Parser.java:128)
    at org.jruby.parser.Parser.parse(Parser.java:77)
    at org.jruby.Ruby.parseEval(Ruby.java:2722)
    at org.jruby.ir.interpreter.Interpreter.prepareIC(Interpreter.java:211)
    at org.jruby.ir.interpreter.Interpreter.evalCommon(Interpreter.java:167)
    at org.jruby.ir.interpreter.Interpreter.evalWithBinding(Interpreter.java:200)
    at org.jruby.RubyKernel.evalCommon(RubyKernel.java:1033)
    at org.jruby.RubyKernel.eval19(RubyKernel.java:1000)
    at org.jruby.RubyKernel$INVOKER$s$0$3$eval19.call(RubyKernel$INVOKER$s$0$3$eval19.gen)
  ...

 
I have Googled the error, but found nothing, so I am a bit stuck! I am using Java 1.8.0.131 (32 bit), Tomcat 8.0.45 (32 bit), Warbler 2.0.4 on Windows 7 Pro.

Any help or suggestions appreciated.
 
Here are the gems from gemfile.lock:
 

GEM
  remote: https://rubygems.org/
  specs:
    actionmailer (4.2.9)
      actionpack (= 4.2.9)
      actionview (= 4.2.9)
      activejob (= 4.2.9)
      mail (~> 2.5, >= 2.5.4)
      rails-dom-testing (~> 1.0, >= 1.0.5)
    actionpack (4.2.9)
      actionview (= 4.2.9)
      activesupport (= 4.2.9)
      rack (~> 1.6)
      rack-test (~> 0.6.2)
      rails-dom-testing (~> 1.0, >= 1.0.5)
      rails-html-sanitizer (~> 1.0, >= 1.0.2)
    actionview (4.2.9)
      activesupport (= 4.2.9)
      builder (~> 3.1)
      erubis (~> 2.7.0)
      rails-dom-testing (~> 1.0, >= 1.0.5)
      rails-html-sanitizer (~> 1.0, >= 1.0.3)
    activejob (4.2.9)
      activesupport (= 4.2.9)
      globalid (>= 0.3.0)
    activemodel (4.2.9)
      activesupport (= 4.2.9)
      builder (~> 3.1)
    activerecord (4.2.9)
      activemodel (= 4.2.9)
      activesupport (= 4.2.9)
      arel (~> 6.0)
    activerecord-jdbc-adapter (1.3.23)
      activerecord (>= 2.2, < 5.0)
    activerecord-jdbcpostgresql-adapter (1.3.23)
      activerecord-jdbc-adapter (~> 1.3.23)
      jdbc-postgres (>= 9.1)
    activesupport (4.2.9)
      i18n (~> 0.7)
      minitest (~> 5.1)
      thread_safe (~> 0.3, >= 0.3.4)
      tzinfo (~> 1.1)
    arel (6.0.4)
    builder (3.2.3)
    coffee-rails (4.1.1)
      coffee-script (>= 2.2.0)
      railties (>= 4.0.0, < 5.1.x)
    coffee-script (2.4.1)
      coffee-script-source
      execjs
    coffee-script-source (1.12.2)
    concurrent-ruby (1.0.5-java)
    erubis (2.7.0)
    execjs (2.7.0)
    ffi (1.9.18-java)
    globalid (0.4.0)
      activesupport (>= 4.2.0)
    i18n (0.8.6)
    jbuilder (2.7.0)
      activesupport (>= 4.2.0)
      multi_json (>= 1.2)
    jdbc-postgres (9.4.1206)
    jquery-rails (4.3.1)
      rails-dom-testing (>= 1, < 3)
      railties (>= 4.2.0)
      thor (>= 0.14, < 2.0)
    json (1.8.6-java)
    loofah (2.0.3)
      nokogiri (>= 1.5.9)
    mail (2.6.6)
      mime-types (>= 1.16, < 4)
    mime-types (3.1)
      mime-types-data (~> 3.2015)
    mime-types-data (3.2016.0521)
    minitest (5.10.2)
    multi_json (1.12.1)
    nokogiri (1.8.0-java)
    rack (1.6.8)
    rack-test (0.6.3)
      rack (>= 1.0)
    rails (4.2.9)
      actionmailer (= 4.2.9)
      actionpack (= 4.2.9)
      actionview (= 4.2.9)
      activejob (= 4.2.9)
      activemodel (= 4.2.9)
      activerecord (= 4.2.9)
      activesupport (= 4.2.9)
      bundler (>= 1.3.0, < 2.0)
      railties (= 4.2.9)
      sprockets-rails
    rails-deprecated_sanitizer (1.0.3)
      activesupport (>= 4.2.0.alpha)
    rails-dom-testing (1.0.8)
      activesupport (>= 4.2.0.beta, < 5.0)
      nokogiri (~> 1.6)
      rails-deprecated_sanitizer (>= 1.0.1)
    rails-html-sanitizer (1.0.3)
      loofah (~> 2.0)
    railties (4.2.9)
      actionpack (= 4.2.9)
      activesupport (= 4.2.9)
      rake (>= 0.8.7)
      thor (>= 0.18.1, < 2.0)
    rake (12.0.0)
    rb-fsevent (0.10.2)
    rb-inotify (0.9.10)
      ffi (>= 0.5.0, < 2)
    rdoc (4.3.0)
    sass (3.5.1)
      sass-listen (~> 4.0.0)
    sass-listen (4.0.0)
      rb-fsevent (~> 0.9, >= 0.9.4)
      rb-inotify (~> 0.9, >= 0.9.7)
    sass-rails (5.0.6)
      railties (>= 4.0.0, < 6)
      sass (~> 3.1)
      sprockets (>= 2.8, < 4.0)
      sprockets-rails (>= 2.0, < 4.0)
      tilt (>= 1.1, < 3)
    sdoc (0.4.2)
      json (~> 1.7, >= 1.7.7)
      rdoc (~> 4.0)
    sprockets (3.7.1)
      concurrent-ruby (~> 1.0)
      rack (> 1, < 3)
    sprockets-rails (3.2.0)
      actionpack (>= 4.0)
      activesupport (>= 4.0)
      sprockets (>= 3.0.0)
    therubyrhino (2.0.4)
      therubyrhino_jar (>= 1.7.3)
    therubyrhino_jar (1.7.6)
    thor (0.19.4)
    thread_safe (0.3.6-java)
    tilt (2.0.7)
    turbolinks (5.0.1)
      turbolinks-source (~> 5)
    turbolinks-source (5.0.3)
    tzinfo (1.2.3)
      thread_safe (~> 0.1)
    tzinfo-data (1.2017.2)
      tzinfo (>= 1.0.0)
    uglifier (3.2.0)
      execjs (>= 0.3.0, < 3)

PLATFORMS
  java

DEPENDENCIES
  activerecord-jdbcpostgresql-adapter
  coffee-rails (~> 4.1.0)
  jbuilder (~> 2.0)
  jquery-rails
  rails (= 4.2.9)
  sass-rails (~> 5.0)
  sdoc (~> 0.4.0)
  therubyrhino
  turbolinks
  tzinfo-data
  uglifier (>= 1.3.0)

BUNDLED WITH
   1.15.1