Client does not support authentication protocol requested by server; consider upgrading MySQL client

/!\ FAILSAFE /!\  Tue Mar 18 08:15:27 +0800 2014
Status: 500 Internal Server Error
 Client does not support authentication protocol requested by server; consider upgrading MySQL client
/usr/local/rvm/rubies/ruby-1.8.6-p420/lib/ruby/1.8/mysql.rb:453:in `read'
/usr/local/rvm/rubies/ruby-1.8.6-p420/lib/ruby/1.8/mysql.rb:130:in `real_connect'
/usr/local/rvm/gems/ruby-1.8.6-p420/gems/activerecord-2.3.7/lib/active_record/connection_adapters/mysql_adapter.rb:619:in `connect'
/usr/local/rvm/gems/ruby-1.8.6-p420/gems/activerecord-2.3.7/lib/active_record/connection_adapters/mysql_adapter.rb:203:in `initialize'
/usr/local/rvm/gems/ruby-1.8.6-p420/gems/activerecord-2.3.7/lib/active_record/connection_adapters/mysql_adapter.rb:75:in `new'
/usr/local/rvm/gems/ruby-1.8.6-p420/gems/activerecord-2.3.7/lib/active_record/connection_adapters/mysql_adapter.rb:75:in `mysql_connection'
/usr/local/rvm/gems/ruby-1.8.6-p420/gems/activerecord-2.3.7/lib/active_record/connection_adapters/abstract/connection_pool.rb:223:in `send'
/usr/local/rvm/gems/ruby-1.8.6-p420/gems/activerecord-2.3.7/lib/active_record/connection_adapters/abstract/connection_pool.rb:223:in `new_connection'
/usr/local/rvm/gems/ruby-1.8.6-p420/gems/activerecord-2.3.7/lib/active_record/connection_adapters/abstract/connection_pool.rb:245:in `checkout_new_connection'
/usr/local/rvm/gems/ruby-1.8.6-p420/gems/activerecord-2.3.7/lib/active_record/connection_adapters/abstract/connection_pool.rb:188:in `checkout'
/usr/local/rvm/gems/ruby-1.8.6-p420/gems/activerecord-2.3.7/lib/active_record/connection_adapters/abstract/connection_pool.rb:184:in `loop'
/usr/local/rvm/gems/ruby-1.8.6-p420/gems/activerecord-2.3.7/lib/active_record/connection_adapters/abstract/connection_pool.rb:184:in `checkout'
/usr/local/rvm/rubies/ruby-1.8.6-p420/lib/ruby/1.8/monitor.rb:242:in `synchronize'
/usr/local/rvm/gems/ruby-1.8.6-p420/gems/activerecord-2.3.7/lib/active_record/connection_adapters/abstract/connection_pool.rb:183:in `checkout'
/usr/local/rvm/gems/ruby-1.8.6-p420/gems/activerecord-2.3.7/lib/active_record/connection_adapters/abstract/connection_pool.rb:98:in `connection'
/usr/local/rvm/gems/ruby-1.8.6-p420/gems/activerecord-2.3.7/lib/active_record/connection_adapters/abstract/connection_pool.rb:326:in `retrieve_connection'
/usr/local/rvm/gems/ruby-1.8.6-p420/gems/activerecord-2.3.7/lib/active_record/connection_adapters/abstract/connection_specification.rb:123:in `retrieve_connection'
/usr/local/rvm/gems/ruby-1.8.6-p420/gems/activerecord-2.3.7/lib/active_record/connection_adapters/abstract/connection_specification.rb:115:in `connection'
/usr/local/rvm/gems/ruby-1.8.6-p420/gems/activerecord-2.3.7/lib/active_record/query_cache.rb:9:in `cache'
/usr/local/rvm/gems/ruby-1.8.6-p420/gems/activerecord-2.3.7/lib/active_record/query_cache.rb:28:in `call'
/usr/local/rvm/gems/ruby-1.8.6-p420/gems/activerecord-2.3.7/lib/active_record/connection_adapters/abstract/connection_pool.rb:361:in `call'
/var/www/html/config/initializers/restfulx.rb:18:in `call'

解决方式：SET PASSWORD FOR 'root'@'localhost' = OLD_PASSWORD('newpassword');