When running install_gems.rb the following error is seen
C:/Ruby22-x64/lib/ruby/2.2.0/open3.rb:193:in 'spawn': No such file or directory - C:\Ruby226\bin\gem install rubygems-update -v 2.7.6 --no-ri --no-rdoc (Errno::ENOENT)
from C:/Ruby22-x64/lib/ruby/2.2.0/open3.rb:193:in 'popen_run'
from C:/Ruby22-x64/lib/ruby/2.2.0/open3.rb:93:in 'popen3'
from install_gems.rb:73:in 'run_command'
from install_gems.rb:39:in 'block (2 levels) in main'
from install_gems.rb:37:in 'each'
from install_gems.rb:37:in 'block in main'
from install_gems.rb:35:in 'chdir'
from install_gems.rb:35:in 'main'
from install_gems.rb:84:in '<main>'
This can be caused by having a GEM_COMMAND environment variable that is set to the wrong location.
In the error message it is observed that the Ruby bin directory is Ruby22-x64 but install_gems is looking in Ruby226 for the gem command.
Please note that the documentation contains example GEM_COMMAND variables which may not be applicable to your environment.
Update the GEM_COMMAND environment variable to reflect your actual installation directory. This is the directory you would have chosen when you installed Ruby as shown in the image below:
In the error message above, Ruby is installed in C:\Ruby22-x64 so GEM_COMMAND should be set to C:\Ruby22-x64\bin\gem as shown in the image below: