In_place_edit_for and nil objects

I have a setup with an admin_controller that allows the editing of
details for users on the site with a manage_user method. This I have set
up to use in-place editing in the same manner as “Rails Recipes.”, also
including the in-place editing validation described here:

When trying to update a user record, an error pops up and the following
appears in the development log:

Processing AdminController#set_user_name (for at 2007-09-25
14:06:44) [POST]
Session ID: 0c4a9ab51fa6851c042e1fb38d317b3c
Parameters: {“action”=>“set_user_name”, “id”=>“1”,
“controller”=>“admin”, “value”=>“Joe U…”}
NoMethodError (You have a nil object when you didn’t expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.+):
update_without_callbacks' /usr/lib64/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/callbacks.rb:267:inupdate_without_timestamps’

…and so on.
I have attached the rest in case they are of use.

Does anyone have any ideas as to where I should be looking for the cause
of this?

Milo T. wrote:

When trying to update a user record, an error pops up…

In case anyone was wondering, my users table had an lock_version int
column in it. Removing this fixed the problem.