Error installing rails on os x El Capitan

Question

I'm trying to install rails but when I run: sudo gem install rails -v 4.2.6 I get the following error, I tried some solutions but none worked so far

I think it's a problem with the "nokogiri" gem, this is the output:

ERROR:  Error installing rails:
    ERROR: Failed to build gem native extension.

    /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby extconf.rb
Using pkg-config version 1.1.7
checking if the C compiler accepts ... yes
checking if the C compiler accepts -Wno-error=unused-command-line-argument-hard-error-in-future... no
Building nokogiri using packaged libraries.
Using mini_portile version 2.1.0
checking for iconv.h... yes
checking for gzdopen() in -lz... yes
checking for iconv... yes
************************************************************************
IMPORTANT NOTICE:

Building Nokogiri with a packaged version of libxml2-2.9.4.

Team Nokogiri will keep on doing their best to provide security
updates in a timely manner, but if this is a concern for you and want
to use the system library instead; abort this installation process and
reinstall nokogiri as follows:

    gem install nokogiri -- --use-system-libraries
        [--with-xml2-config=/path/to/xml2-config]
        [--with-xslt-config=/path/to/xslt-config]

If you are using Bundler, tell it to use the option:

    bundle config build.nokogiri --use-system-libraries
    bundle install

Note, however, that nokogiri is not fully compatible with arbitrary
versions of libxml2 provided by OS/package vendors.
************************************************************************
Extracting libxml2-2.9.4.tar.gz into tmp/x86_64-apple-darwin15/ports/libxml2/2.9.4... OK
Running 'configure' for libxml2 2.9.4... OK
Running 'compile' for libxml2 2.9.4... ERROR, review '/Library/Ruby/Gems/2.0.0/gems/nokogiri-1.6.8/ext/nokogiri/tmp/x86_64-apple-darwin15/ports/libxml2/2.9.4/compile.log' to see what happened. Last lines are:
========================================================================
  CCLD     libxml2.la
  CC       testdso.lo
  CCLD     testdso.la
  CC       xmllint.o
  CCLD     xmllint
ld: warning: ignoring file /usr/local/Cellar/xz/5.2.2/lib/liblzma.dylib, file was built for x86_64 which is not the architecture being linked (i386): /usr/local/Cellar/xz/5.2.2/lib/liblzma.dylib
Undefined symbols for architecture i386:
  "_lzma_auto_decoder", referenced from:
      _xz_head in libxml2.a(xzlib.o)
  "_lzma_code", referenced from:
      _xz_decomp in libxml2.a(xzlib.o)
  "_lzma_end", referenced from:
      ___libxml2_xzclose in libxml2.a(xzlib.o)
  "_lzma_properties_decode", referenced from:
      _is_format_lzma in libxml2.a(xzlib.o)
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [xmllint] Error 1
make[1]: *** [all-recursive] Error 1
make: *** [all] Error 2
========================================================================
*** 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=/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby
    --help
    --clean
    --use-system-libraries
    --enable-static
    --disable-static
    --with-zlib-dir
    --without-zlib-dir
    --with-zlib-include
    --without-zlib-include=${zlib-dir}/include
    --with-zlib-lib
    --without-zlib-lib=${zlib-dir}/lib
    --enable-cross-build
    --disable-cross-build
/Library/Ruby/Gems/2.0.0/gems/mini_portile2-2.1.0/lib/mini_portile2/mini_portile.rb:366:in `block in execute': Failed to complete compile task (RuntimeError)
    from /Library/Ruby/Gems/2.0.0/gems/mini_portile2-2.1.0/lib/mini_portile2/mini_portile.rb:337:in `chdir'
    from /Library/Ruby/Gems/2.0.0/gems/mini_portile2-2.1.0/lib/mini_portile2/mini_portile.rb:337:in `execute'
    from /Library/Ruby/Gems/2.0.0/gems/mini_portile2-2.1.0/lib/mini_portile2/mini_portile.rb:111:in `compile'
    from /Library/Ruby/Gems/2.0.0/gems/mini_portile2-2.1.0/lib/mini_portile2/mini_portile.rb:150:in `cook'
    from extconf.rb:364:in `block (2 levels) in process_recipe'
    from extconf.rb:257:in `block in chdir_for_build'
    from extconf.rb:256:in `chdir'
    from extconf.rb:256:in `chdir_for_build'
    from extconf.rb:363:in `block in process_recipe'
    from extconf.rb:262:in `tap'
    from extconf.rb:262:in `process_recipe'
    from extconf.rb:555:in `<main>'


Gem files will remain installed in /Library/Ruby/Gems/2.0.0/gems/nokogiri-1.6.8 for inspection.
Results logged to /Library/Ruby/Gems/2.0.0/gems/nokogiri-1.6.8/ext/nokogiri/gem_make.out

Answer 1

The error comes from a conflict of xz and nokogiri over libxml. Official issue and solution for nokogiri is: https://github.com/sparklemotion/nokogiri/issues/1483

(similar issue reminder: always re-run xcode-select --install after installing Xcode 8)

Solution A

You can install nokogiri using Xcode's libxml2:

gem install nokogiri -- --with-xml2-include=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/libxml2 --use-system-libraries

Solution B

If you don't need it, uninstall xz:

brew uninstall xz

Solution C

If you need it, reinstall xz in a compatible way:

brew install xz --universal

Solution D

You can install libxml2:

brew install libxml2

Answer 2

Assuming you're using homebrew: brew install libxml2 ; then install rails again.

Answer 3

I fixed this by running

$brew uninstall xz

And then running again

$ sudo gem install nokogiri -v '1.6.8'

Solution inspired by: https://tickets.puppetlabs.com/browse/BKR-841

PS: I don't know the side effects of removing xz, but at least it got my nokogiri to build :)

Answer 4

Firstly, install nokogiri for mac with this command.

sudo gem install nokogiri -v '1.6.6.2' -- --use-system-libraries --with-xml2-include=/usr/include/libxml2 --with-xml2-lib=/usr/lib

Then install rails as usual.