NoMethodError: undefined method `size' for nil:NilClass

[rming]

Yosemite 10.10.1 ruby 2.0.0p481 (2014-05-08 revision 45883) [universal.x86_64-darwin14] gem 2.0.14 Vagrant 1.7.2

rming@rmingwang:~/vagrant/work$ vagrant plugin install vagrant-bindfs
Installing the 'vagrant-bindfs' plugin. This can take a few minutes...
Bundler, the underlying system Vagrant uses to install plugins,
reported an error. The error is shown below. These errors are usually
caused by misconfigured plugin installations or transient network
issues. The error from Bundler is:

An error occurred while installing rdoc (4.2.0), and Bundler cannot continue.
Make sure that `gem install rdoc -v '4.2.0'` succeeds before bundling.

NoMethodError: undefined method `size' for nil:NilClass
rming@rmingwang:~/vagrant/work$ gem list

*** LOCAL GEMS ***

bigdecimal (1.2.0)
CFPropertyList (2.2.8)
io-console (0.4.2)
json (1.7.7)
libxml-ruby (2.6.0)
minitest (4.3.2)
nokogiri (1.5.6)
psych (2.0.0)
rake (0.9.6)
rdoc (4.2.0, 4.0.0)
sqlite3 (1.3.7)
test-unit (2.0.0.0)
vagrant-bindfs (0.3.2)

[gael-ian]

Could you post the output of both vagrant plugin list and vagrant plugin install vagrant-bindfs --verbose ?

[rming]

Thanks for your reply , it's a network problem thank for the GFW...