# TypeError

**URL:** <https://www.ruby-forum.com/t/typeerror/67158>\
**Category:** Rails\
**Created:** [February 13, 2006, 6:13pm UTC](https://www.ruby-forum.com/t/typeerror/67158 "2006-02-13T18:13:45Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\
**Post date:** [February 13, 2006, 6:13pm UTC](https://www.ruby-forum.com/t/typeerror/67158/1 "2006-02-13T18:13:45Z")

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What might cause this error?

TypeError (singleton can’t be dumped):  
/usr/lib/ruby/1.8/pstore.rb:159:in `dump' /usr/lib/ruby/1.8/pstore.rb:159:in`dump’  
/usr/lib/ruby/1.8/pstore.rb:138:in `transaction' /usr/lib/ruby/1.8/cgi/session/pstore.rb:90:in`update’  
/usr/lib/ruby/1.8/cgi/session/pstore.rb:97:in `close' /usr/lib/ruby/1.8/cgi/session.rb:330:in`close’  
/usr/lib/ruby/gems/1.8/gems/actionpack-1.11.2/lib/  
action\_controller/base.rb:914:in `close_session' /usr/lib/ruby/gems/1.8/gems/actionpack-1.11.2/lib/ action_controller/base.rb:372:in`process\_without\_session\_management\_support’  
/usr/lib/ruby/gems/1.8/gems/actionpack-1.11.2/lib/  
action\_controller/session\_management.rb:116:in `process' /usr/lib/ruby/gems/1.8/gems/rails-1.0.0/lib/dispatcher.rb:38:in`dispatch’  
/usr/lib/ruby/gems/1.8/gems/rails-1.0.0/lib/webrick\_server.rb:  
117:in `handle_dispatch' /usr/lib/ruby/gems/1.8/gems/rails-1.0.0/lib/webrick_server.rb: 83:in`service’  
/usr/lib/ruby/1.8/webrick/httpserver.rb:104:in `service' /usr/lib/ruby/1.8/webrick/httpserver.rb:65:in`run’  
/usr/lib/ruby/1.8/webrick/server.rb:155:in `start_thread' /usr/lib/ruby/1.8/webrick/server.rb:144:in`start’  
/usr/lib/ruby/1.8/webrick/server.rb:144:in `start_thread' /usr/lib/ruby/1.8/webrick/server.rb:94:in`start’  
/usr/lib/ruby/1.8/webrick/server.rb:89:in `each' /usr/lib/ruby/1.8/webrick/server.rb:89:in`start’  
/usr/lib/ruby/1.8/webrick/server.rb:79:in `start' /usr/lib/ruby/1.8/webrick/server.rb:79:in`start’  
/usr/lib/ruby/gems/1.8/gems/rails-1.0.0/lib/webrick\_server.rb:  
69:in `dispatch' /usr/lib/ruby/gems/1.8/gems/rails-1.0.0/lib/commands/servers/ webrick.rb:59 /usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:18:in`require\_\_’  
/usr/lib/ruby/site\_ruby/1.8/rubygems/custom\_require.rb:18:in  
`require' /usr/lib/ruby/gems/1.8/gems/activesupport-1.2.5/lib/ active_support/dependencies.rb:214:in`require’  
/usr/lib/ruby/gems/1.8/gems/rails-1.0.0/lib/commands/server.rb:28  
/usr/lib/ruby/site\_ruby/1.8/rubygems/custom\_require.rb:18:in  
`require__' /usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:18:in`require’  
/usr/lib/ruby/gems/1.8/gems/activesupport-1.2.5/lib/  
active\_support/dependencies.rb:214:in `require’  
./script/server:3

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<div class="post-metadata">

**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\
**Post date:** [February 13, 2006, 6:32pm UTC](https://www.ruby-forum.com/t/typeerror/67158/2 "2006-02-13T18:32:21Z")

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Something in the session can’t be serialized?

b

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<div class="post-metadata">

**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\
**Post date:** [February 13, 2006, 6:37pm UTC](https://www.ruby-forum.com/t/typeerror/67158/3 "2006-02-13T18:37:06Z")

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Don’t store into session objects that have singlton methods:

$ irb  
irb(main):001:0\> o = Object.new  
=\> #Object:0x356838  
irb(main):002:0\> def o.test; puts ‘test’ end  
=\> nil  
irb(main):003:0\> Marshal.d  
Marshal.display Marshal.dup Marshal.dump  
irb(main):003:0\> Marshal.dump(o)  
TypeError: singleton can’t be dumped  
from (irb):3:in `dump' from (irb):3:in`binding’  
from :0  
irb(main):004:0\>

Kent.

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<div class="post-metadata">

**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\
**Post date:** [February 13, 2006, 9:23pm UTC](https://www.ruby-forum.com/t/typeerror/67158/4 "2006-02-13T21:23:09Z")

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Wow, that’s weird… why’s that? I knew threads and resources could be  
serialized, but anything with a singleton method?  
Oh wait, I guess that makes sense because once you’ve added a the method  
to the instance it no longer meets the class  
definition. Right?

b