Rails pg gem Incompatible library version

问题:

I'm getting the following 'incompatible library version' error when I try and access my Ruby on Rails website in development mode.

incompatible library version - /var/www/vhosts/launch.site.com/httpdocs/vendor/bundle/ruby/2.2.0/gems/pg-0.18.4/lib/pg_ext.so (LoadError)   /var/www/vhosts/launch.site.com/httpdocs/vendor/bundle/ruby/2.2.0/gems/pg-0.18.4/lib/pg.rb:4:in `require'   /var/www/vhosts/launch.site.com/httpdocs/vendor/bundle/ruby/2.2.0/gems/pg-0.18.4/lib/pg.rb:4:in `'   /usr/local/rvm/gems/ruby-2.2.3/gems/bundler-1.10.6/lib/bundler/runtime.rb:76:in `require'   /usr/local/rvm/gems/ruby-2.2.3/gems/bundler-1.10.6/lib/bundler/runtime.rb:76:in `block (2 levels) in require'   /usr/local/rvm/gems/ruby-2.2.3/gems/bundler-1.10.6/lib/bundler/runtime.rb:72:in `each'   /usr/local/rvm/gems/ruby-2.2.3/gems/bundler-1.10.6/lib/bundler/runtime.rb:72:in `block in require'   /usr/local/rvm/gems/ruby-2.2.3/gems/bundler-1.10.6/lib/bundler/runtime.rb:61:in `each'   /usr/local/rvm/gems/ruby-2.2.3/gems/bundler-1.10.6/lib/bundler/runtime.rb:61:in `require'   /usr/local/rvm/gems/ruby-2.2.3/gems/bundler-1.10.6/lib/bundler.rb:134:in `require'   /var/www/vhosts/launch.site.com/httpdocs/config/application.rb:7:in `'   /var/www/vhosts/launch.site.com/httpdocs/config/environment.rb:2:in `require'   /var/www/vhosts/launch.site.com/httpdocs/config/environment.rb:2:in `'   config.ru:3:in `require'   config.ru:3:in `block in 
'   /var/www/vhosts/launch.site.com/httpdocs/vendor/bundle/ruby/2.2.0/gems/rack-1.6.4/lib/rack/builder.rb:55:in `instance_eval'   /var/www/vhosts/launch.site.com/httpdocs/vendor/bundle/ruby/2.2.0/gems/rack-1.6.4/lib/rack/builder.rb:55:in `initialize'   config.ru:1:in `new'   config.ru:1:in `
'   /usr/share/passenger/helper-scripts/rack-preloader.rb:110:in `eval'   /usr/share/passenger/helper-scripts/rack-preloader.rb:110:in `preload_app'   /usr/share/passenger/helper-scripts/rack-preloader.rb:156:in `'   /usr/share/passenger/helper-scripts/rack-preloader.rb:30:in `'   /usr/share/passenger/helper-scripts/rack-preloader.rb:29:in `
'

I've looked at what libraries pg_ext.so is trying to access and using ldd and here's the output:

$ ldd pg-0.18.4/lib/pg_ext.so     linux-vdso.so.1 =>  (0x00007ffc14a7c000)     libruby.so.1.8 => /usr/lib64/libruby.so.1.8 (0x00007fe98291a000)     libpq.so.5 => /usr/lib64/libpq.so.5 (0x00007fe9826f1000)     libpthread.so.0 => /lib64/libpthread.so.0 (0x00007fe9824cb000)     librt.so.1 => /lib64/librt.so