YAML error while starting sup

YAML error while starting sup

Usually after a gem update you might see this error when starting sup:

$ sup
/home/myuser/.gem/ruby/2.2.0/gems/sup-0.21.0/lib/sup.rb:30:in `yaml_properties': undefined method `yaml_tag' for Redwood::MBox:Class (NoMethodError)
    from /home/myuser/.gem/ruby/2.2.0/gems/sup-0.21.0/lib/sup/mbox.rb:10:in `<class:MBox>'
    from /home/myuser/.gem/ruby/2.2.0/gems/sup-0.21.0/lib/sup/mbox.rb:6:in `<module:Redwood>'
    from /home/myuser/.gem/ruby/2.2.0/gems/sup-0.21.0/lib/sup/mbox.rb:4:in `<top (required)>'
    from /usr/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:69:in `require'
    from /usr/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:69:in `require'
    from /home/myuser/.gem/ruby/2.2.0/gems/sup-0.21.0/lib/sup.rb:423:in `<top (required)>'
    from /usr/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:69:in `require'
    from /usr/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:69:in `require'
    from /home/myuser/.gem/ruby/2.2.0/gems/sup-0.21.0/bin/sup:21:in `<top (required)>'
    from /home/myuser/.gem/ruby/2.2.0/bin/sup:23:in `load'
    from /home/myuser/.gem/ruby/2.2.0/bin/sup:23:in `<main>'

The current fix is to remove the psych gem as it is packaged with ruby on default.

References:

• #403 - Updated gems. Sup now crashes with an error about "undefined method" 'yaml_tag'
• #409 - yaml_properties': undefined method yaml_tag'