Why I got many ignoring messages when I run pry?

Question

I am using rbenv and have installed a 2.3.1 version:

➜  ~ rbenv versions
  system
* 2.3.1 (set by /Users/s_zhang/.rbenv/version)

When I run pry in my terminal, I got:

➜  ~ pry
Ignoring bcrypt-3.1.11 because its extensions are not built.  Try: gem pristine bcrypt --version 3.1.11
Ignoring bcrypt-3.1.10 because its extensions are not built.  Try: gem pristine bcrypt --version 3.1.10
Ignoring binding_of_caller-0.7.2 because its extensions are not built.  Try: gem pristine binding_of_caller --version 0.7.2
Ignoring byebug-9.0.6 because its extensions are not built.  Try: gem pristine byebug --version 9.0.6
Ignoring byebug-9.0.5 because its extensions are not built.  Try: gem pristine byebug --version 9.0.5
Ignoring curb-0.9.3 because its extensions are not built.  Try: gem pristine curb --version 0.9.3
Ignoring debug_inspector-0.0.2 because its extensions are not built.  Try: gem pristine debug_inspector --version 0.0.2
Ignoring bcrypt-3.1.11 because its extensions are not built.  Try: gem pristine bcrypt --version 3.1.11
Ignoring bcrypt-3.1.10 because its extensions are not built.  Try: gem pristine bcrypt --version 3.1.10
Ignoring binding_of_caller-0.7.2 because its extensions are not built.  Try: gem pristine binding_of_caller --version 0.7.2
Ignoring byebug-9.0.6 because its extensions are not built.  Try: gem pristine byebug --version 9.0.6
Ignoring byebug-9.0.5 because its extensions are not built.  Try: gem pristine byebug --version 9.0.5
Ignoring curb-0.9.3 because its extensions are not built.  Try: gem pristine curb --version 0.9.3
Ignoring debug_inspector-0.0.2 because its extensions are not built.  Try: gem pristine debug_inspector --version 0.0.2
Ignoring ffi-1.9.14 because its extensions are not built.  Try: gem pristine ffi --version 1.9.14
Ignoring hitimes-1.2.4 because its extensions are not built.  Try: gem pristine hitimes --version 1.2.4
Ignoring mysql2-0.4.4 because its extensions are not built.  Try: gem pristine mysql2 --version 0.4.4
Ignoring mysql2-0.3.20 because its extensions are not built.  Try: gem pristine mysql2 --version 0.3.20
Ignoring nio4r-1.2.1 because its extensions are not built.  Try: gem pristine nio4r --version 1.2.1
Ignoring nokogiri-1.6.8.1 because its extensions are not built.  Try: gem pristine nokogiri --version 1.6.8.1
Ignoring nokogiri-1.6.8 because its extensions are not built.  Try: gem pristine nokogiri --version 1.6.8
Ignoring nokogiri-1.6.7 because its extensions are not built.  Try: gem pristine nokogiri --version 1.6.7
Ignoring oj-2.17.5 because its extensions are not built.  Try: gem pristine oj --version 2.17.5
Ignoring puma-3.6.2 because its extensions are not built.  Try: gem pristine puma --version 3.6.2
Ignoring puma-3.6.0 because its extensions are not built.  Try: gem pristine puma --version 3.6.0
Ignoring puma-2.16.0 because its extensions are not built.  Try: gem pristine puma --version 2.16.0
Ignoring puma-2.15.3 because its extensions are not built.  Try: gem pristine puma --version 2.15.3
Ignoring ruby-ll-2.1.2 because its extensions are not built.  Try: gem pristine ruby-ll --version 2.1.2
Ignoring sqlite3-1.3.12 because its extensions are not built.  Try: gem pristine sqlite3 --version 1.3.12
Ignoring therubyracer-0.12.2 because its extensions are not built.  Try: gem pristine therubyracer --version 0.12.2
Ignoring unf_ext-0.0.7.2 because its extensions are not built.  Try: gem pristine unf_ext --version 0.0.7.2
Ignoring websocket-driver-0.6.4 because its extensions are not built.  Try: gem pristine websocket-driver --version 0.6.4
Ignoring yajl-ruby-1.2.1 because its extensions are not built.  Try: gem pristine yajl-ruby --version 1.2.1
[1] pry(main)>

My gem list:

➜  ~ gem list

*** LOCAL GEMS ***

ansi (1.5.0)
ast (2.3.0)
bcrypt (3.1.11)
bigdecimal (1.2.8)
binding_of_caller (0.7.2)
byebug (9.0.6)
coderay (1.1.1)
curb (0.9.3)
debug_inspector (0.0.2)
did_you_mean (1.0.0)
ffi (1.9.14)
hitimes (1.2.4)
io-console (0.4.5)
json (1.8.3)
libv8 (3.16.14.17 x86_64-darwin-16)
method_source (0.8.2)
mini_portile2 (2.1.0)
minitest (5.8.3)
mysql2 (0.4.5)
net-telnet (0.1.1)
nio4r (1.2.1)
nokogiri (1.6.8.1)
oj (2.18.0)
power_assert (0.2.6)
pry (0.10.4)
pry-remote (0.1.8)
psych (2.0.17)
puma (3.6.2)
rake (10.4.2)
rdoc (4.2.1)
ref (2.0.0)
ruby-ll (2.1.2)
slop (3.6.0)
sqlite3 (1.3.12)
test-unit (3.1.5)
therubyracer (0.12.2)
unf_ext (0.0.7.2)
websocket-driver (0.6.4)
websocket-extensions (0.1.2)
yajl-ruby (1.3.0)

I have find a way like gem pristine --all. But not work for me.

Answer 1

Had this issue today after I switched ruby from 2.3 to 2.4 via RVM

I solved this by

gem uninstall bundler
gem install bundler
gem pristine --all