% puppet Traceback (most recent call last): 14: from /usr/bin/puppet:9:in `<main>' 13: from /usr/bin/puppet:9:in `load' 12: from /usr/lib64/ruby/gems/2.5.0/gems/puppet-6.11.1/bin/puppet:4:in `<top (required)>' 11: from /usr/lib64/ruby/site_ruby/2.5.0/rubygems/core_ext/kernel_require.rb:34:in `require' 10: from /usr/lib64/ruby/site_ruby/2.5.0/rubygems/core_ext/kernel_require.rb:130:in `rescue in require' 9: from /usr/lib64/ruby/site_ruby/2.5.0/rubygems/core_ext/kernel_require.rb:130:in `require' 8: from /usr/lib64/ruby/gems/2.5.0/gems/puppet-6.11.1/lib/puppet/util/command_line.rb:12:in `<top (required)>' 7: from /usr/lib64/ruby/site_ruby/2.5.0/rubygems/core_ext/kernel_require.rb:54:in `require' 6: from /usr/lib64/ruby/site_ruby/2.5.0/rubygems/core_ext/kernel_require.rb:54:in `require' 5: from /usr/lib64/ruby/gems/2.5.0/gems/puppet-6.11.1/lib/puppet.rb:38:in `<top (required)>' 4: from /usr/lib64/ruby/gems/2.5.0/gems/puppet-6.11.1/lib/puppet.rb:308:in `<module:Puppet>' 3: from /usr/lib64/ruby/site_ruby/2.5.0/rubygems/core_ext/kernel_require.rb:54:in `require' 2: from /usr/lib64/ruby/site_ruby/2.5.0/rubygems/core_ext/kernel_require.rb:54:in `require' 1: from /usr/lib64/ruby/gems/2.5.0/gems/puppet-6.11.1/lib/puppet/runtime.rb:3:in `<top (required)>' /usr/lib64/ruby/gems/2.5.0/gems/puppet-6.11.1/lib/puppet/runtime.rb:4:in `<class:Runtime>': uninitialized constant Puppet::Runtime::Singleton (NameError) Did you mean? SignalException I have the problem on multiple machines after updating from 6.10.1. It seems a simple fix works: sed -i -e "1arequire 'singleton'" /usr/lib64/ruby/gems/2.5.0/gems/puppet-6.11.1/lib/puppet/runtime.rb