Installing Nokogiri

To see why this extension failed to compile, please check the mkmf.log which can be found here:

/Users/myuser2/.gem/ruby/2.7.0/extensions/arm64-darwin-20/2.7.0/racc-1.5.2/mkmf.log

extconf failed, exit code 1

#### Solution 1 - Compiler toolchain

Racc needs the same compiler toolchain to be present as any Gem with a C extension. See [Appendix A: The Compiler Toolchain](#appendix-a-the-compiler-toolchain).


#### Solution 2 - Avoid installing Racc

Ruby 3.0 comes with Racc 1.5.x as a "builtin gem", so you could update to Ruby 3!

Ruby 2.7 comes with Racc 1.4.x as a "builtin gem", so you could use that version instead of trying to upgrade. Update to Ruby 2.7 and add a line like `gem "racc", "~> 1.4.0"` to prevent bundler from trying to upgrade.



### [Linux] `/usr/bin/ld: cannot find -lgmp`

If you're compiling the `ruby` platform gem, and if you've installed Ruby using RVM, [you may require libgmp](https://github.com/rvm/rvm/issues/3509).

#### Symptoms

Gem installation fails with an error message like:

``` sh
/home/user/.rvm/rubies/ruby-2.2.3/lib/ruby/2.2.0/mkmf.rb:456:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.

And examination of your mkmf.log file shows:

/usr/bin/ld: cannot find -lgmp

Solution

Run sudo apt-get install libgmp-dev.

[MacOS] xcode-select errors with a 'network problem'

If you're compiling the ruby platform gem ...

Symptoms

You see this dialog when you run the commands to update xcode commandline tools:

Solution

Run this command to turn off forced-authentication with Apple Software Update:

sudo defaults delete /Library/Preferences/com.apple.SoftwareUpdate CatalogURL

[MacOS] error: use of undeclared identifier 'LZMA_OK'

If you're compiling the ruby platform gem ...

Symptoms

An error during Nokogiri installation mentions an undeclared identifier LZMA_OK:

xmlIO.c:1450:52: error: use of undeclared identifier 'LZMA_OK'
    ret =  (__libxml2_xzclose((xzFile) context) == LZMA_OK ) ? 0 : -1;
                                                   ^
1 error generated.

Diagnosis

When using Homebrew, there are several libraries that use a formula called xz (including the_silver_searcher and imagemagick), which by default install a version of liblzma that is incompatible with most Ruby builds. (Homebrew installs only the 64-bit version of the library, but most Ruby builds are universal.) This can be fixed in a couple of ways:

Solution 1

The most reliable solution appears to be temporarily unlinking xz and relinking it during an install of nokogiri:

brew unlink xz
gem install nokogiri # or bundle install
brew link xz

Solution 2

The other solution is to use a Homebrew-installed libxml2, as suggested in Installing Using Standard System Libraries.

brew install libxml2
gem install nokogiri -- --use-system-libraries \
    --with-xml2-include=$(brew --prefix libxml2)/include/libxml2

or if you're using bundler:

bundle config build.nokogiri --use-system-libraries \
    --with-xml2-include=$(brew --prefix libxml2)/include/libxml2
bundle install

When working with this, be certain to use $(brew --prefix libxml2) because it will use the correct location for your Homebrew install.

[MacOS] libiconv is missing

Xcode 10 on macOS Mojave moves the system headers out of /usr/include and so Nokogiri will fail to build when you're compiling the ruby platform gem.

Symptoms

You'll see an error similar to this:

``` text hl_lines="3" Building nokogiri using packaged libraries.

libiconv is missing. please visit http://nokogiri.org/tutorials/installing_nokogiri.html for help with installing dependencies.

*** extconf.rb failed *** Could not create Makefile due to some reason, probably lack of necessary libraries and/or headers.

#### Solution

A temporary workaround to allow previous releases of Nokogiri to build is to install the extra headers package mentioned in the Xcode 10 release notes:

``` sh
open /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg

You can also install the headers package from the command line (e.g. for a build script or a CI server):

sudo installer -pkg /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg -target /

[MacOS] General MacOS Tips

If you're seeing other problems:

• Make sure ruby is compiled with the latest clang compiler.
• Binary gems and ruby should be compiled with the same compiler/environment.
• If you have multiple versions of Xcode installed, make sure you use the right xcode-select.
• Try Installing Using Standard System Libraries.

Appendix A: The Compiler Toolchain

A good way to tell if you've got your basic Ruby C extension compiler toolchain installed correctly is to try installing the bcrypt gem which has a smaller, self-contained C extension. If you can gem install bcrypt, you're all set!

Reminder: if you're installing a native gem, you don't need to do this.

Ubuntu or Debian-based Distros

sudo apt-get install build-essential ruby-dev

Fedora, Red Hat, and CentOS

dnf install -y make gcc rpm-build ruby-devel

Windows

Please visit RubyInstaller and make sure you install a version "With Devkit".

MacOS

First, make sure you have the latest version of RubyGems and xcode commandline tools:

gem update --system
xcode-select --install # Then agree to the terms, even if you have done this before!

Agree to the Xcode license:

sudo xcodebuild -license