I had a similar issue on Ubuntu something was funny in Net::HTTP and was sending requests that twitter couldn't process (400 response). Here's what I put in my environment.rb to fix it:

module Twitter
class Search

def fetch(force=false)
  if @fetch.nil? || force
    query = @query.dup

    query[:q] = query[:q].join(' ')
    query[:format] = 'json' #This line is the hack and whole reason we're monkey-patching at all.

    response = self.class.get('http://search.twitter.com/search', :query => query, :format => :json)

    @fetch = Mash.new(response)
  end

  @fetch
end

end end


labzero. Thanks a bunch. This worked for us! I tried doing a HTTP.new('search.twitter.com', nil).get('/search.json?q=obama') in irb and this would yield the same result. Your patch sidesteps that somehow. This problem just started occuring...I think after the ruby BigDecimal patch on EngineYard I believe, but that may be a coincidence. Any further insights?

Glad it worked for you! I have no idea why it's happening on my Ubuntu servers, they haven't changed and I just started using the twitter gem... The bug didn't happen locally on Leopard.

I've been experiencing this consistently with 2 apps hosted on Heroku. I'll try the patch.
UPDATE: Solved my problem on Heroku! Thanks!

Solved also my problem on heroku. Thanks!

This is still acting up for me, even when I drop that code into my code. Still get the error randomly:

/var/lib/gems/1.8/gems/httparty-0.4.3/lib/httparty/response.rb:15:in send': undefined methodstringify_keys' for #<String:0x7fe66b8cc4a0> (NoMethodError)

from /var/lib/gems/1.8/gems/httparty-0.4.3/lib/httparty/response.rb:15:in `method_missing'
from /var/lib/gems/1.8/gems/mash-0.0.3/lib/mash.rb:131:in `deep_update'
from /var/lib/gems/1.8/gems/mash-0.0.3/lib/mash.rb:50:in `initialize'
from pullterm.rb:63:in `new'
from pullterm.rb:63:in `fetch'
from /var/lib/gems/1.8/gems/twitter-0.6.14/lib/twitter/search.rb:109:in `each'
from pullterm.rb:86:in `query_term'
from pullterm.rb:127

I am seeing this error as well (but i'm only using HTTParty, but assuming the issue is the same with the Twitter gem?), but it only seems to be on large data sets (like @barackobama's twitter friends):

/Library/Ruby/Gems/1.8/gems/crack-0.1.3/lib/crack/json.rb:14:in `parse': Invalid JSON string (Crack::ParseError)

Some of it 'seems' to be unicode issues potentially. I've had to write some stuff to get around the followers/tweets that blow it up, but I can't figure out which ones are causing it. Its always the same tweet/user however, which makes me think of some unicode issue causing improper JSON that blows up Crack.

I'm getting the same error regardless of the user I'm trying to unfollow (friendship_destroy), with crack-0.1.4.