Why error when installing bundle?

Question

Ruby on Rails

I'm trying to install redmine 3.
Ubuntu 15.04
Apache2
I put it like this www.redmine.org/projects/redmine/wiki/RusRedmineInstall
When I start

bundle install --without development test

gives an error message:

Fetching gem metadata from https://rubygems.org/.........
Fetching version metadata from https://rubygems.org/..
Resolving dependencies....
Using rake 10.4.2
Using i18n 0.7.0
Using json 1.8.3
Using minitest 5.8.2
Using thread_safe 0.3.5
Using tzinfo 1.2.2
Using activesupport 4.2.4
Using builder 3.2.2
Using erubis 2.7.0
Using mini_portile 0.6.2
Installing nokogiri 1.6.6.2 with native extensions

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    /usr/bin/ruby2.1 extconf.rb --use-system-libraries
checking if the C compiler accepts ... yes
Building nokogiri using system libraries.
libxml2 version 2.6.21 or later is required!
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
  --with-opt-dir
  --without-opt-dir
  --with-opt-include
  --without-opt-include=${opt-dir}/include
  --with-opt-lib
  --without-opt-lib=${opt-dir}/lib
  --with-make-prog
  --without-make-prog
  --srcdir=.
  --curdir
  --ruby=/usr/bin/ruby2.1
  --help
  --clean
  --use-system-libraries
  --with-zlib-dir
  --without-zlib-dir
  --with-zlib-include
  --without-zlib-include=${zlib-dir}/include
  --with-zlib-lib
  --without-zlib-lib=${zlib-dir}/lib
  --with-xml2-dir
  --without-xml2-dir
  --with-xml2-include
  --without-xml2-include=${xml2-dir}/include
  --with-xml2-lib
  --without-xml2-lib=${xml2-dir}/lib
  --with-libxml-2.0-config
  --without-libxml-2.0-config
  --with-pkg-config
  --without-pkg-config
  --with-xslt-dir
  --without-xslt-dir
  --with-xslt-include
  --without-xslt-include=${xslt-dir}/include
  --with-xslt-lib
  --without-xslt-lib=${xslt-dir}/lib
  --with-libxslt-config
  --without-libxslt-config
  --with-exslt-dir
  --without-exslt-dir
  --with-exslt-include
  --without-exslt-include=${exslt-dir}/include
  --with-exslt-lib
  --without-exslt-lib=${exslt-dir}/lib
  --with-libexslt-config
  --without-libexslt-config

extconf failed, exit code 1

Gem files will remain installed in /tmp/bundler20151027-4688-161sygmnokogiri-1.6.6.2/gems/nokogiri-1.6.6.2 for inspection.
Results logged to /tmp/bundler20151027-4688-161sygmnokogiri-1.6.6.2/extensions/x86_64-linux/2.1.0/nokogiri-1.6.6.2/gem_make.out
An error occurred while installing nokogiri (1.6.6.2), and Bundler cannot continue.
Make sure that `gem install nokogiri -v '1.6.6.2'` succeeds before bundling.

Answer 1

libxml2 version 2.6.21 or later is required!

Uncle will read error messages?